Import strxcpyx from upstream

This commit imports strxcpyx from upstream.  This is upstream commit

    d5a89d7dc17a5ba5cf4fc71f82963c5c94a31c3d

Note: there were also some very minor code cleanups to

	accelerometer.c: line 187
	collect.c: lines 35, 140
	libudev-device.c: line 780
	libudev-hwdb.c: line 300

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>