Import the asan runtime library into GCC tree

Import the asan runtime library into GCC tree

This patch imports the runtime library in the GCC tree, ensures that
-lasan is passed to the linker when -faddress-sanitizer is used and
sets up the build system accordingly.

ChangeLog:

	* configure.ac: Add libsanitizer to target_libraries.
	* Makefile.def: Ditto.
	* configure: Regenerate.
	* Makefile.in: Regenerate.
	* libsanitizer: New directory for asan runtime.  Contains an empty
	tsan directory.

gcc/ChangeLog:

	* gcc.c (LINK_COMMAND_SPEC): Add -laddress-sanitizer to link
	command if -faddress-sanitizer is on.

libsanitizer:

	Initial checkin: migrate asan runtime from llvm.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@193441 138bc75d-0d04-0410-961f-82ee72b054a4