Don't manually link libgcc in CMake.

Doing this here causes libgcc to be linked ahead of the STL, which
breaks unwinding and therefore exception handling.

Test: ./run_tests.py
Bug: android/ndk#379
Change-Id: I63cbbdc125fdc3231a21f3354c1b1cfb129ac12b

build/cmake/android.toolchain.cmake

@@ -546,7 +546,7 @@ foreach(library ${ANDROID_STL_SHARED_LIBRARIES})
 	list(APPEND ANDROID_CXX_STANDARD_LIBRARIES
 		"${ANDROID_NDK}/sources/cxx-stl/${ANDROID_STL_PREFIX}/libs/${ANDROID_ABI}/lib${library}.so")
 endforeach()
-set(CMAKE_C_STANDARD_LIBRARIES_INIT "-lgcc -latomic -lm")
+set(CMAKE_C_STANDARD_LIBRARIES_INIT "-latomic -lm")
 set(CMAKE_CXX_STANDARD_LIBRARIES_INIT "${CMAKE_C_STANDARD_LIBRARIES_INIT}")
 if(ANDROID_CXX_STANDARD_LIBRARIES)
 	string(REPLACE ";" "\" \"" ANDROID_CXX_STANDARD_LIBRARIES "\"${ANDROID_CXX_STANDARD_LIBRARIES}\"")