Improve the test in bitfields.m4

Using a named bitfield with a width more than 0 means we won't hit
weirdness caused by the bitfield not really needing to exist.  Changing
int to long long means we won't have trouble with some arch where size
of int is 1 or 2.

libobjc/ChangeLog:

2015-05-04  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>

	* configure: Regenerate.

config/ChangeLog:

2015-05-04  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>

	* bitfields.m4: Change int to long long, and use bitfields of
	width 1 instead of 0.

From-SVN: r222794