[PATCH 0/1] MR5275: configure: Don't explicitly enable -Wenum-conversion on Clang.

[Jacek Caban (＠jacek)]

Clang enables -Wenum-conversion by default anyway, we add it to CFLAGS to enable them on GCC.
When explicitly enabled, Clang also enables additional warnings. Some of those warnings, like
-Wenum-enum-conversion, are too strict to be practical with win32, so avoid enabling them.

Fixes warnings with LLVM git.