d: Add `@no_sanitize' attribute to compiler and library.

d: Add `@no_sanitize' attribute to compiler and library.

The `@no_sanitize' attribute disables a particular sanitizer for this
function, analogous to `__attribute__((no_sanitize))'.  The library also
defines `@noSanitize' to be compatible with the LLVM D compiler's
`ldc.attributes'.

gcc/d/ChangeLog:

	* d-attribs.cc (d_langhook_attribute_table): Add no_sanitize.
	(d_handle_no_sanitize_attribute): New function.

libphobos/ChangeLog:

	* libdruntime/gcc/attributes.d (no_sanitize): Define.
	(noSanitize): Define.

gcc/testsuite/ChangeLog:

	* gdc.dg/asan/attr_no_sanitize1.d: New test.
	* gdc.dg/ubsan/attr_no_sanitize2.d: New test.