codecov: avoid inlining functions for correct execution counts

This adds a compiler option -fno-inline for code coverage on
architectures which supports doing code coverage. This also
modifies the ALWAYS_INLINE macro to not do any inlining. This
needs to be done so code coverage can count the number of
executions to the correct lines.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>