evas: let's be more resistant even with things that should never happen.

Fix CID 1193212.

src/modules/evas/engines/gl_common/evas_gl_context.c

@@ -372,6 +372,7 @@ _evas_gl_common_version_check()
      return 0;
 
    tmp = strchr(version, '.');
+   if (!tmp) return 0;
    /* the first '.' always exists */
    *tmp = '\0';
    major = atoi(version);