cmake: add more checks for folly-config.h generation

Summary:
Update the CMake build files to perform additional checks to set configuration
macros in folly-config.h

I believe this should largely bring the CMake build on-par with (or even better
than) the autoconf build scripts.  I believe that the CMake build scripts now
perform all of the checks necessary to set macros in folly-config.h correctly.

The autoconf-based configure script also appears to have a number of bugs:
in several places it accidentally uses different macro names than the ones
checked in the source code.  Some of it's checks are also broken, and fail to
detect features correctly due to compilation errors in the check.

Reviewed By: yfeldblum

Differential Revision: D6735699

fbshipit-source-id: 5ce48f1deddd63c9d52fcccd5d5ccf6ca35e9a0d