Fix the pod spec lint issue, change 4 components into 3, the webp subspec includes both WebP encoding && decoding

Author: dreampiggy

libwebp.podspec

@@ -19,38 +19,23 @@ Pod::Spec.new do |s|
     'USER_HEADER_SEARCH_PATHS' => '$(inherited) ${PODS_ROOT}/libwebp/ ${PODS_TARGET_SRCROOT}/'
   }
   s.preserve_path = 'src'
-  s.default_subspecs = 'dec', 'enc', 'demux', 'mux'
+  s.default_subspecs = 'webp', 'demux', 'mux'
 
-  # common code, used by actual subspecs
-  s.subspec 'core' do |ss|
-    ss.source_files = 'src/utils/*.{h,c}', 'src/dsp/*.{h,c}', 'src/webp/types.h', 'src/webp/format_constants.h'
-    ss.public_header_files = 'src/webp/types.h', 'src/webp/format_constants.h'
-  end
-
-  # webp decoding
-  s.subspec 'dec' do |ss|
-    ss.dependency 'libwebp/core'
-    ss.source_files = 'src/dec/*.{h,c}', 'src/webp/decode.h'
-    ss.public_header_files = 'src/webp/decode.h'
-  end
-
-  # webp encoding
-  s.subspec 'enc' do |ss|
-    ss.dependency 'libwebp/core'
-    ss.source_files = 'src/enc/*.{h,c}', 'src/webp/encode.h'
-    ss.public_header_files = 'src/webp/encode.h'
+  # webp decoding && encoding
+  s.subspec 'webp' do |ss|
+    ss.source_files = 'src/webp/decode.h', 'src/webp/encode.h', 'src/webp/types.h', 'src/webp/mux_types.h', 'src/webp/format_constants.h', 'src/utils/*.{h,c}', 'src/dsp/*.{h,c}', 'src/dec/*.{h,c}', 'src/enc/*.{h,c}'
+    ss.public_header_files = 'src/webp/decode.h', 'src/webp/encode.h', 'src/webp/types.h', 'src/webp/mux_types.h', 'src/webp/format_constants.h'
   end
 
   # animated webp decoding
   s.subspec 'demux' do |ss|
-    ss.dependency 'libwebp/dec'
-    ss.source_files = 'src/demux/*.{h,c}', 'src/webp/demux.h', 'src/webp/mux_types.h'
-    ss.public_header_files = 'src/webp/demux.h', 'src/webp/mux_types.h'
+    ss.dependency 'libwebp/webp'
+    ss.source_files = 'src/demux/*.{h,c}', 'src/webp/demux.h'
+    ss.public_header_files = 'src/webp/demux.h'
   end
 
   # animated webp encoding
   s.subspec 'mux' do |ss|
-    ss.dependency 'libwebp/enc'
     ss.dependency 'libwebp/demux'
     ss.source_files = 'src/mux/*.{h,c}', 'src/webp/mux.h'
     ss.public_header_files = 'src/webp/mux.h'