Revert double thing

Some tests are failing now that didn't fail in contbuild. Revert until I can look at it.

hphp/runtime/base/string_data.cpp

@@ -824,7 +824,7 @@ int64_t StringData::toInt64(int base /* = 10 */) const {
 
 double StringData::toDouble() const {
   StringSlice s = slice();
-  if (s.len) return strtod(s.ptr, nullptr);
+  if (s.len) return zend_strtod(s.ptr, nullptr);
   return 0;
 }