Fix webp compile warnings on windows

This fix was landed with:
https://codereview.chromium.org/1280073002/

The above CL was reverted due to an unrelated bug in libwebp.

The above CL contains multiple components, and I think that
reverting this part of the change was unintentional.

BUG=skia:

Review URL: https://codereview.chromium.org/1286903003

diff --git a/third_party/libwebp/webp/config.h b/third_party/libwebp/webp/config.h
index 62ade94..b01473c 100644 (file)
--- a/third_party/libwebp/webp/config.h
+++ b/third_party/libwebp/webp/config.h
@@ -14,14 +14,14 @@
 // file, which replaces the checks in endian_inl.h to decide whether we have
 // particular builtins.
 
-#ifdef __builtin_bswap64(x)
+#ifdef __builtin_bswap64
     #define HAVE_BUILTIN_BSWAP64
 #endif
 
-#ifdef __builtin_bswap32(x)
+#ifdef __builtin_bswap32
     #define HAVE_BUILTIN_BSWAP32
 #endif
 
-#ifdef __builtin_bswap16(x)
+#ifdef __builtin_bswap16
     #define HAVE_BUILTIN_BSWAP16
 #endif