Fix Android build with cmake 2.6.3

3rdparty/libpng/CMakeLists.txt

@@ -30,6 +30,7 @@ if(MSVC)
 endif(MSVC)
 
 add_library(${PNG_LIBRARY} STATIC ${lib_srcs} ${lib_hdrs})
+target_link_libraries(${PNG_LIBRARY} ${ZLIB_LIBRARY})
 
 if(UNIX)
   if(CMAKE_COMPILER_IS_GNUCXX OR CV_ICC)

android/android.toolchain.cmake

@@ -796,6 +796,7 @@ set( CMAKE_ASM_COMPILER_ID GNU )
 set( CMAKE_ASM_COMPILER_WORKS TRUE )
 set( CMAKE_ASM_COMPILER_FORCED TRUE )
 set( CMAKE_COMPILER_IS_GNUASM 1)
+set( CMAKE_ASM_SOURCE_FILE_EXTENSIONS s S asm )
 
 # NDK flags
 if( ARMEABI OR ARMEABI_V7A )