Restore ancient -Waddress for weak symbols [PR33925].

Restore ancient -Waddress for weak symbols [PR33925].

Resolves:
PR c/33925 - gcc -Waddress lost some useful warnings
PR c/102867 - -Waddress from macro expansion in readelf.c

gcc/c-family/ChangeLog:

	PR c++/33925
	PR c/102867
	* c-common.c (decl_with_nonnull_addr_p): Call maybe_nonzero_address
	and improve handling tof defined symbols.

gcc/c/ChangeLog:

	PR c++/33925
	PR c/102867
	* c-typeck.c (maybe_warn_for_null_address): Suppress warnings for
	code resulting from macro expansion.

gcc/cp/ChangeLog:

	PR c++/33925
	PR c/102867
	* typeck.c (warn_for_null_address): Suppress warnings for code
	resulting from macro expansion.

gcc/ChangeLog:

	PR c++/33925
	PR c/102867
	* doc/invoke.texi (-Waddress): Update.

gcc/testsuite/ChangeLog:

	PR c++/33925
	PR c/102867
	* g++.dg/warn/Walways-true-2.C: Adjust to avoid a valid warning.
	* c-c++-common/Waddress-5.c: New test.
	* c-c++-common/Waddress-6.c: New test.
	* g++.dg/warn/Waddress-7.C: New test.
	* gcc.dg/Walways-true-2.c: Adjust to avoid a valid warning.
	* gcc.dg/weak/weak-3.c: Expect a warning.