Add anything specifying a threads library to ex_libs

Even -pthread gets treated that way.  The reason to do this is so it
ends up in 'Libs.private' in libcrypto.pc.

Fixes #3884
Reviewed-by: NBernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/5134)

Configurations/10-main.conf

@@ -196,6 +196,7 @@ my %targets = (
                                               debug   => "-O0 -g",
                                               release => "-O3 -fomit-frame-pointer"),
                                        threads("-pthread")),
+        ex_libs          => add(threads("-pthread")),
         bn_ops           => "BN_LLONG",
         shared_cflag     => "-fPIC",
         shared_ldflag    => "-shared -static-libgcc",
@@ -215,6 +216,7 @@ my %targets = (
                                               debug   => "-O0 -g",
                                               release => "-O3"),
                                        threads("-pthread")),
+        ex_libs          => add(threads("-pthread")),
         bn_ops           => "SIXTY_FOUR_BIT_LONG",
         perlasm_scheme   => "elf",
         shared_cflag     => "-fPIC",
@@ -260,6 +262,7 @@ my %targets = (
                                               debug   => "-O0 -g",
                                               release => "-O3"),
                                        threads("-pthread")),
+        ex_libs          => add(threads("-pthread")),
         bn_ops           => "BN_LLONG RC4_CHAR",
         shared_cflag     => "-fPIC",
         shared_ldflag    => "-shared",
@@ -416,7 +419,7 @@ my %targets = (
                                            debug   => "-O0 -g",
                                            release => "-O3"),
                                     threads("-pthread")),
-        ex_libs          => add("-Wl,+s -ldld"),
+        ex_libs          => add("-Wl,+s -ldld", threads("-pthread")),
         bn_ops           => "BN_LLONG",
         thread_scheme    => "pthreads",
         dso_scheme       => "dl",
@@ -530,7 +533,7 @@ my %targets = (
                                            debug   => "-O0 -g",
                                            release => "-O3"),
                                     threads("-pthread")),
-        ex_libs          => add("-ldl"),
+        ex_libs          => add("-ldl", threads("-pthread")),
         bn_ops           => "SIXTY_FOUR_BIT",
         thread_scheme    => "pthreads",
         dso_scheme       => "dlfcn",
@@ -547,7 +550,7 @@ my %targets = (
                                            debug   => "-O0 -g",
                                            release => "-O3"),
                                     threads("-pthread")),
-        ex_libs          => add("-ldl"),
+        ex_libs          => add("-ldl", threads("-pthread")),
         bn_ops           => "SIXTY_FOUR_BIT_LONG",
         thread_scheme    => "pthreads",
         dso_scheme       => "dlfcn",
@@ -579,7 +582,7 @@ my %targets = (
         cc               => "gcc",
         cflags           => combine("-std=c9x -D_XOPEN_SOURCE=500 -D_OSF_SOURCE -O3",
                                     threads("-pthread")),
-        ex_libs          => "-lrt",    # for mlock(2)
+        ex_libs          => add("-lrt", threads("-pthread")), # for mlock(2)
         bn_ops           => "SIXTY_FOUR_BIT_LONG",
         thread_scheme    => "pthreads",
         dso_scheme       => "dlfcn",
@@ -591,7 +594,7 @@ my %targets = (
         cc               => "cc",
         cflags           => combine("-std1 -D_XOPEN_SOURCE=500 -D_OSF_SOURCE -tune host -fast -readonly_strings",
                                     threads("-pthread")),
-        ex_libs          => "-lrt",    # for mlock(2)
+        ex_libs          => add("-lrt", threads("-pthread")), # for mlock(2)
         bn_ops           => "SIXTY_FOUR_BIT_LONG",
         thread_scheme    => "pthreads",
         dso_scheme       => "dlfcn",
@@ -613,7 +616,7 @@ my %targets = (
                                            debug   => "-O0 -g",
                                            release => "-O3"),
                                     threads("-pthread")),
-        ex_libs          => add("-ldl"),
+        ex_libs          => add("-ldl", threads("-pthread")),
         bn_ops           => "BN_LLONG RC4_CHAR",
         thread_scheme    => "pthreads",
         dso_scheme       => "dlfcn",
@@ -957,6 +960,7 @@ my %targets = (
                                            debug   => "-O0 -g",
                                            release => "-O3"),
                                     threads("-pthread -D_THREAD_SAFE -D_REENTRANT")),
+        ex_libs          => add(threads("-pthread")),
         enable           => add("devcryptoeng"),
         bn_ops           => "BN_LLONG",
         thread_scheme    => "pthreads",
@@ -1161,6 +1165,7 @@ my %targets = (
                                            debug   => "-O0 -g",
                                            release => "-O"),
                                     threads("-pthread")),
+        ex_libs          => add(threads("-pthread")),
         sys_id           => "AIX",
         bn_ops           => "BN_LLONG RC4_CHAR",
         thread_scheme    => "pthreads",
@@ -1178,6 +1183,7 @@ my %targets = (
                                            debug   => "-O0 -g",
                                            release => "-O"),
                                     threads("-pthread")),
+        ex_libs          => add(threads("-pthread")),
         sys_id           => "AIX",
         bn_ops           => "SIXTY_FOUR_BIT_LONG RC4_CHAR",
         thread_scheme    => "pthreads",
@@ -1625,7 +1631,7 @@ my %targets = (
         cc               => "gcc",
         cflags           => combine("-DL_ENDIAN -O3 -fomit-frame-pointer -Wall",
                                     threads("-pthread")),
-        ex_libs          => add("-ldl"),
+        ex_libs          => add("-ldl", threads("-pthread")),
         bn_ops           => "BN_LLONG",
         thread_scheme    => "pthreads",
         dso_scheme       => "dlfcn",