Remove old config that used non-exist util script

Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5016)

Configurations/10-main.conf

@@ -1234,18 +1234,6 @@ my %targets = (
         thread_scheme    => "(unknown)",
     },
 
-# OS/390 Unix an EBCDIC-based Unix system on IBM mainframe
-# You need to compile using the c89.sh wrapper in the tools directory, because the
-# IBM compiler does not like the -L switch after any object modules.
-#
-    "OS390-Unix" => {
-        inherit_from     => [ "BASE_unix" ],
-        cc               => "c89.sh",
-        cflags           => "-O -DB_ENDIAN -DCHARSET_EBCDIC -DNO_SYS_PARAM_H  -D_ALL_SOURCE",
-        bn_ops           => "THIRTY_TWO_BIT RC4_CHAR",
-        thread_scheme    => "(unknown)",
-    },
-
 #### Visual C targets
 #
 # Win64 targets, WIN64I denotes IA-64 and WIN64A - AMD64