cpp: test: Allow stream operators to be found by ADL
cpp: test: Use constants of correct type in equality comparison
cpp: test: Only run death tests if supported by the platform
cpp: test: Remove unused variable in variantpixelbuffer
cpp: test: Split pixelbuffer into multiple translation units

This instantiates the templated tests for one pixel type
per unit.  This is to work around travis failures due to
this file failing to build due to an internal compiler
error and/or memory problems on the build node.  The tests
run are unchanged.
Merge pull request #1295 from rleigh-dundee/cpp-bsd-fixes

C++: clang++/llvm 3.3 fixes