Fixed #1444 and the master build thanks to 5034c334be

SDWebImage.podspec

@@ -37,7 +37,10 @@ Pod::Spec.new do |s|
 
   s.subspec 'WebP' do |webp|
     webp.source_files = 'SDWebImage/UIImage+WebP.{h,m}'
-    webp.xcconfig = { 'GCC_PREPROCESSOR_DEFINITIONS' => '$(inherited) SD_WEBP=1' }
+    webp.xcconfig = { 
+      'GCC_PREPROCESSOR_DEFINITIONS' => '$(inherited) SD_WEBP=1',
+      'USER_HEADER_SEARCH_PATHS' => '$(inherited) $(SRCROOT)/libwebp/src'
+    }
     webp.dependency 'SDWebImage/Core'
     webp.dependency 'libwebp'
   end

SDWebImage/UIImage+WebP.m

@@ -12,7 +12,7 @@
 #if !COCOAPODS
 #import "webp/decode.h"
 #else
-#import "libwebp/webp/decode.h"
+#import "webp/decode.h"
 #endif
 
 // Callback for CGDataProviderRelease