darwinssl: fix undefined $ssllib warning in runtests.pl

I also added --with-darwinssl to the list of SSL options in configure.

configure.ac

@@ -2293,7 +2293,7 @@ fi
 
 if test "x$OPENSSL_ENABLED$GNUTLS_ENABLED$NSS_ENABLED$POLARSSL_ENABLED$AXTLS_ENABLED$CYASSL_ENABLED$WINSSL_ENABLED$DARWINSSL_ENABLED" = "x"; then
   AC_MSG_WARN([SSL disabled, you will not be able to use HTTPS, FTPS, NTLM and more.])
-  AC_MSG_WARN([Use --with-ssl, --with-gnutls, --with-polarssl, --with-cyassl, --with-nss, --with-axtls or --with-winssl to address this.])
+  AC_MSG_WARN([Use --with-ssl, --with-gnutls, --with-polarssl, --with-cyassl, --with-nss, --with-axtls, --with-winssl, or --with-darwinssl to address this.])
 else
   # SSL is enabled, genericly
   AC_SUBST(SSL_ENABLED)

tests/runtests.pl

@@ -220,6 +220,7 @@ my $has_yassl;   # built with yassl
 my $has_polarssl; # built with polarssl
 my $has_axtls;    # built with axTLS
 my $has_winssl;   # built with WinSSL (Schannel/SSPI)
+my $has_darwinssl;# build with DarwinSSL (Secure Transport)
 
 my $has_shared = "unknown";  # built shared
 
@@ -2258,6 +2259,10 @@ sub checksystem {
                $has_axtls=1;
                $ssllib="axTLS";
            }
+           elsif ($libcurl =~ /securetransport/i) {
+               $has_darwinssl=1;
+               $ssllib="DarwinSSL";
+           }
         }
         elsif($_ =~ /^Protocols: (.*)/i) {
             # these are the protocols compiled in to this libcurl
@@ -2682,6 +2687,11 @@ sub singletest {
                 next;
             }
         }
+        elsif($f eq "DarwinSSL") {
+            if($has_darwinssl) {
+                next;
+            }
+        }
         elsif($f eq "unittest") {
             if($debug_build) {
                 next;