2017-06-12 Wilco Dijkstra <wdijkstr@arm.com>

There is no longer a need for string2.h, so remove it and all mention of it.
Move the redirect for __stpcpy to include/string.h since it is still required
until all internal uses have been renamed.
This fixes several linknamespace/localplt failures when building with -Os.

	[BZ #15105]
	[BZ #19463]
	* include/string.h: Add internal redirect for __stpcpy.
	* string/Makefile: Remove bits/string2.h.
	* string/string.h: Update comment.
	* string/string-inlines.c: Remove bits/string2.h include and comment.
	* string/bits/string2.h: Remove file.