Fix no_fsanitize_address effective target

Fix no_fsanitize_address effective target

The implementation of the no_fsanitize_address effective target was copied
from asan-dg.exp without realizing that it does not work outside of this
context (there is a comment explaining why).  As a consequence, it always
returns 0, so for example the directive in gnat.dg/asan1.adb:

{ dg-skip-if "no address sanitizer" { no_fsanitize_address } }

does not work.  This led some people to add the nonsensical:

{ dg-require-effective-target no_fsanitize_address }

to sanitizer tests, e.g. g++.dg/warn/uninit-pr93100.C, thus disabling them
everywhere instead of just for the problematic targets.

gcc/testsuite/
	* lib/target-supports.exp (no_fsanitize_address): Add missing bits.
	* gcc.dg/pr91441.c: Likewise.
	* gcc.dg/pr96260.c: Likewise.
	* gcc.dg/pr96307.c: Likewise.

	* g++.dg/abi/anon4.C: Likewise.