Avoid MemoryLeakOperatorOverloadsTest failure on clang-3.2

if CMAKE_BUILD_TYPE is RelWithDebInfo or Release,
MemoryLeakOperatorOverloadsTest fails.

cpputest/tests/MemoryLeakOperatorOverloadsTest.cpp:344: error: Failure in TEST(OutOfMemoryTestsForOperatorNew, FailingNewArrayOperatorThrowsAnExceptionWhenUsingStdCppNewWithoutOverride)
	Should have thrown an exception!
.
cpputest/tests/MemoryLeakOperatorOverloadsTest.cpp:334: error: Failure in TEST(OutOfMemoryTestsForOperatorNew, FailingNewOperatorThrowsAnExceptionWhenUsingStdCppNewWithoutOverride)
	Should have thrown an exception!