Bug#18818 configure: No longer finds OpenSSL on Mac OS X

 - Eval shrext_cmds variable before using it
 - Moved from acinclude.m4 to openssl.m4 and zlib.m4 when merging 4.1 -> 5.0

config/ac-macros/openssl.m4

 AC_DEFUN([MYSQL_FIND_OPENSSL], [
   incs="$1"
   libs="$2"
+  eval shrexts=\"$shrext_cmds\"
   case "$incs---$libs" in
     ---)
       for d in /usr/ssl/include /usr/local/ssl/include /usr/include \
@@ -15,7 +16,7 @@ AC_DEFUN([MYSQL_FIND_OPENSSL], [
 /usr/lib /usr/lib64 /opt/ssl/lib /opt/openssl/lib \
 /usr/freeware/lib32 /usr/local/lib/ ; do
       # Just to be safe, we test for ".so" anyway
-      if test -f $d/libssl.a || test -f $d/libssl.so || test -f $d/libssl$shrext_cmds ; then
+      if test -f $d/libssl.a || test -f $d/libssl.so || test -f $d/libssl$shrext ; then
         OPENSSL_LIB=$d
       fi
       done
@@ -28,7 +29,7 @@ AC_DEFUN([MYSQL_FIND_OPENSSL], [
         OPENSSL_INCLUDE=-I$incs
       fi
       # Just to be safe, we test for ".so" anyway
-      if test -f $libs/libssl.a || test -f $libs/libssl.so || test -f $libs/libssl$shrext_cmds ; then
+      if test -f $libs/libssl.a || test -f $libs/libssl.so || test -f $libs/libssl$shrext ; then
         OPENSSL_LIB=$libs
       fi
       ;;

config/ac-macros/zlib.m4

@@ -90,8 +90,9 @@ case $SYSTEM_TYPE in
         ;;
       *)
         # Just to be safe, we test for ".so" anyway
+        eval shrexts=\"$shrext_cmds\"
         if test \( -f "$mysql_zlib_dir/lib/libz.a"  -o -f "$mysql_zlib_dir/lib/libz.so" -o \
-                   -f "$mysql_zlib_dir/lib/libz$shrext_cmds" \) \
+                   -f "$mysql_zlib_dir/lib/libz$shrext" \) \
                 -a -f "$mysql_zlib_dir/include/zlib.h"; then
           ZLIB_INCLUDES="-I$mysql_zlib_dir/include"
           ZLIB_LIBS="-L$mysql_zlib_dir/lib -lz"