Revision 302180

Fix bitstring allocation on 32-bit platforms

sys/sys/bitstring.h
	Fix a rounding calculation that could undersize a bitstring on
	32-bit platforms.

tests/sys/sys/bitstring_test.h
	Add a test for bitstr_size

PR:		210260
Reported by:	Mark Millard
Reviewed by:	gibbs
Approved by:	re (marius)
Sponsored by:	Spectra Logic Corp
Differential Revision:	https://reviews.freebsd.org/D6848