Added -pthread compiler flag for Unix builds and changed -lpthread to -pthread.
Merge remote-tracking branch 'upstream/next' into MAID-322_fix_cryptest_with_gcc

Conflicts:
	cmake_modules/standard_flags.cmake
Merge remote-tracking branch 'upstream/next' into MAID-322_fix_cryptest_with_gcc

Conflicts:
	cmake_modules/standard_flags.cmake
Added warning message for missing ccache.
Updated to avoid multiple warnings about ccache in a single CMake run.
Minor style fix.
Removed another instance of '-pthread' being added to Clang linker flags.
Merge pull request #160 from Fraser999/MAID-322_fix_cryptest_with_gcc

MAID-322: Added -pthread compiler flag for Unix builds and changed -lpthread to -p...