[ 83%] Building CXX object Source/WebCore/CMakeFiles/WebCoreTestSupport.dir/__/__/DerivedSources/WebCore/InternalSettingsGenerated.cpp.o
/usr/lib64/gcc/x86_64-slackware-linux/5.3.0/../../../../x86_64-slackware-linux/bin/ld.gold: error: cannot find -lwebp
../../lib/libWebCoreGTK.a(../../lib/../Source/WebCore/CMakeFiles/WebCore.dir/platform/image-decoders/webp/WEBPImageDecoder.cpp.o):WEBPImageDecoder.cpp:function WebCore::WEBPImageDecoder::clear(): error: undefined reference to 'WebPIDelete'
../../lib/libWebCoreGTK.a(../../lib/../Source/WebCore/CMakeFiles/WebCore.dir/platform/image-decoders/webp/WEBPImageDecoder.cpp.o):WEBPImageDecoder.cpp:function WebCore::WEBPImageDecoder::decode(bool): error: undefined reference to 'WebPIUpdate'
../../lib/libWebCoreGTK.a(../../lib/../Source/WebCore/CMakeFiles/WebCore.dir/platform/image-decoders/webp/WEBPImageDecoder.cpp.o):WEBPImageDecoder.cpp:function WebCore::WEBPImageDecoder::decode(bool): error: undefined reference to 'WebPGetFeaturesInternal'
../../lib/libWebCoreGTK.a(../../lib/../Source/WebCore/CMakeFiles/WebCore.dir/platform/image-decoders/webp/WEBPImageDecoder.cpp.o):WEBPImageDecoder.cpp:function WebCore::WEBPImageDecoder::decode(bool): error: undefined reference to 'WebPINewRGB'
collect2: error: ld returned 1 exit status
Source/WebKit2/CMakeFiles/WebKit2.dir/build.make:18596: recipe for target 'lib/libwebkit2gtk-4.0.so.37.13.11' failed
make[2]: *** [lib/libwebkit2gtk-4.0.so.37.13.11] Error 1
CMakeFiles/Makefile2:1312: recipe for target 'Source/WebKit2/CMakeFiles/WebKit2.dir/all' failed
make[1]: *** [Source/WebKit2/CMakeFiles/WebKit2.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....
[ 83%] Linking CXX static library ../../lib/libWebCoreTestSupport.a
[ 84%] Built target WebCoreTestSupport
[ 84%] Linking CXX static library ../../lib/libWebCorePlatformGTK2.a
[ 84%] Built target WebCorePlatformGTK2
Makefile:149: recipe for target 'all' failed
make: *** [all] Error 2