Merge from gcc: use "cannot" instead of "can not" in libiberty and include.

Merge from gcc: use "cannot" instead of "can not" in libiberty and include.

2019-01-09  Sandra Loosemore  <sandra@codesourcery.com>

	Merge from GCC:

	2019-01-09  Sandra Loosemore  <sandra@codesourcery.com>

	PR other/16615 [2/5]

	include/
	* libiberty.h: Mechanically replace "can not" with "cannot".
	* plugin-api.h: Likewise.

	libiberty/
	* cp-demangle.c: Mechanically replace "can not" with "cannot".
	* floatformat.c: Likewise.
	* strerror.c: Likewise.