* Fix conversions build with gcc 4.8.5 armhf.
Re-named fplib.c to fplib.cpp.
Updated the conditions under which fplib.cpp will be included in the build by CMake.
* Build: Added a global archtiecture variable, CLConform_TARGET_ARCH.
The reset of the build can query this variable whenever archtiecture specific options are required. The current supported values of this variable are "ARM", "x86", and "x86_64".
This change also replaces all existing locations where CMAKE_SYSTEM_PROCESSOR was queried.
* Build: Added ARM64 as a valid value for CLConform_TARGET_ARCH.
* Conversions: Don't build fplib.cpp for ARM64.