Preserve CFLAGS/LDFLAGS for curl ssl check

We need to add the curl-specific flags, but we also need to preserve
the general flags, to keep around important stuff like -m32.

Author: nikic

ext/curl/config.m4

@@ -26,9 +26,9 @@ if test "$PHP_CURL" != "no"; then
     AC_DEFINE([HAVE_CURL_SSL], [1], [Have cURL with  SSL support])
 
     save_CFLAGS="$CFLAGS"
-    CFLAGS=$CURL_CFLAGS
+    CFLAGS="$CFLAGS $CURL_CFLAGS"
     save_LDFLAGS="$LDFLAGS"
-    LDFLAGS=$CURL_LIBS
+    LDFLAGS="$LDFLAGS $CURL_LIBS"
 
     AC_PROG_CPP
     AC_MSG_CHECKING([for openssl support in libcurl])