CocoaPods/Specs — pull request #9133 by marcus1877 (2014-03-12 13:14:06+00:00)
Title: It's in a deeper folder in kazmatch

s.xcconfig = { 'HEADER_SEARCH_PATHS' => '"${PODS_ROOT}/cocos2d/external/kazmath/include/**"' }
Instead of
s.xcconfig = { 'HEADER_SEARCH_PATHS' => '"${PODS_ROOT}/cocos2d/external/kazmath/include"' }
because the real path for headers of kazmath is
YourCocos2dSourceCodeDownloadedFromInternet/external/kazmath/include/kazmath/