commonlib/helpers.h: handle interaction with other environments

There are compiler settings and interactions with other
header files that should be handled. First use __typeof__
instead of typeof because 'std' modes don't accept typeof.
The __typeof__ variant works equally well on clang. The
other change is to guard the helper macros so as not to
trigger redefinition errors.

BUG=chrome-os-partner:44827
BRANCH=None
TEST=Built cbfstool including commonlib/helpers.h

Change-Id: I58890477cb17df14a9fa8b7af752a7c70769cf36
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/11773
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
1 file changed