Merge pull request SDWebImage#1196 from unlucio/webp-case

Fixing casing for #import "webp/decode.h"

Author: bpoplauschi

SDWebImage/UIImage+WebP.m

@@ -8,7 +8,7 @@
 
 #ifdef SD_WEBP
 #import "UIImage+WebP.h"
-#import "webp/decode.h"
+#import "WebP/decode.h"
 
 // Callback for CGDataProviderRelease
 static void FreeImageData(void *info, const void *data, size_t size)