Implement protection of global variables

Implement protection of global variables

This patch implements the protection of global variables.  See the
comments appended to the beginning of the asan.c file.

	* varasm.c: Include asan.h.
	(assemble_noswitch_variable): Grow size by asan_red_zone_size
	if decl is asan protected.
	(place_block_symbol): Likewise.
	(assemble_variable): If decl is asan protected, increase
	DECL_ALIGN if needed, and for decls emitted using
	assemble_variable_contents append padding zeros after it.
	* Makefile.in (varasm.o): Depend on asan.h.
	* asan.c: Include output.h.
	(asan_pp, asan_pp_initialized, asan_ctor_statements): New variables.
	(asan_pp_initialize, asan_pp_string): New functions.
	(asan_emit_stack_protection): Use asan_pp{,_initialized}
	instead of local pp{,_initialized} vars, use asan_pp_initialize
	and asan_pp_string helpers.
	(asan_needs_local_alias, asan_protect_global,
	asan_global_struct, asan_add_global): New functions.
	(asan_finish_file): Protect global vars that can be protected. Use
	asan_ctor_statements instead of ctor_statements
	* asan.h (asan_protect_global): New prototype.
	(asan_red_zone_size): New inline function.

Co-Authored-By: Wei Mi <wmi@google.com>
From-SVN: r193437