crypto/*: address standard-compilance nits.

Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NKurt Roeckx <kurt@roeckx.be>
(Merged from https://github.com/openssl/openssl/pull/6745)

crypto/conf/conf_def.c

@@ -27,6 +27,10 @@
 # endif
 #endif
 
+#ifndef S_ISDIR
+# define S_ISDIR(a) (((a) & S_IFMT) == S_IFDIR)
+#endif
+
 /*
  * The maximum length we can grow a value to after variable expansion. 64k
  * should be more than enough for all reasonable uses.
@@ -656,7 +660,7 @@ static BIO *process_include(char *include, OPENSSL_DIR_CTX **dirctx,
         return NULL;
     }
 
-    if ((st.st_mode & S_IFDIR) == S_IFDIR) {
+    if (S_ISDIR(st.st_mode)) {
         if (*dirctx != NULL) {
             CONFerr(CONF_F_PROCESS_INCLUDE,
                     CONF_R_RECURSIVE_DIRECTORY_INCLUDE);

crypto/store/loader_file.c

@@ -35,6 +35,10 @@
 # define stat    _stat
 #endif
 
+#ifndef S_ISDIR
+# define S_ISDIR(a) (((a) & S_IFMT) == S_IFDIR)
+#endif
+
 /*-
  *  Password prompting
  *  ------------------
@@ -839,7 +843,7 @@ static OSSL_STORE_LOADER_CTX *file_open(const OSSL_STORE_LOADER *loader,
         return NULL;
     }
 
-    if ((st.st_mode & S_IFDIR) == S_IFDIR) {
+    if (S_ISDIR(st.st_mode)) {
         /*
          * Try to copy everything, even if we know that some of them must be
          * NULL for the moment.  This prevents errors in the future, when more

crypto/ui/ui_openssl.c

@@ -43,7 +43,7 @@
  * If unistd.h defines _POSIX_VERSION, we conclude that we are on a POSIX
  * system and have sigaction and termios.
  */
-#  if defined(_POSIX_VERSION)
+#  if defined(_POSIX_VERSION) && _POSIX_VERSION>=199309L
 
 #   define SIGACTION
 #   if !defined(TERMIOS) && !defined(TERMIO) && !defined(SGTTY)