libsanitizer: Add option to bootstrap using HWASAN

This is an analogous option to --bootstrap-asan to configure.  It allows
bootstrapping GCC using HWASAN.

For the same reasons as for ASAN we have to avoid using the HWASAN
sanitizer when compiling libiberty and the lto-plugin.

Also add a function to query whether -fsanitize=hwaddress has been
passed.

ChangeLog:

	* configure: Regenerate.
	* configure.ac: Add --bootstrap-hwasan option.

config/ChangeLog:

	* bootstrap-hwasan.mk: New file.

gcc/ChangeLog:

	* doc/install.texi: Document new option.

libiberty/ChangeLog:

	* configure: Regenerate.
	* configure.ac: Avoid using sanitizer.

lto-plugin/ChangeLog:

	* Makefile.am: Avoid using sanitizer.
	* Makefile.in: Regenerate.