Testsuite: fix analyzer tests on Darwin

Testsuite: fix analyzer tests on Darwin

On macOS, system headers redefine by default some macros (memcpy,
memmove, etc) to checked versions, which defeats the analyzer. We
want to turn this off.
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104042

gcc/testsuite/ChangeLog:

	PR analyzer/104042
	* gcc.dg/analyzer/analyzer.exp: Pass -D_FORTIFY_SOURCE=0 on Darwin.
	* gcc.dg/analyzer/fd-bind.c: Add missing <string.h> header.
	* gcc.dg/analyzer/fd-datagram-socket.c: Likewise.
	* gcc.dg/analyzer/fd-listen.c: Likewise.
	* gcc.dg/analyzer/fd-socket-misuse.c: Likewise.
	* gcc.dg/analyzer/fd-stream-socket-active-open.c: Likewise.
	* gcc.dg/analyzer/fd-stream-socket-passive-open.c: Likewise.
	* gcc.dg/analyzer/fd-stream-socket.c: Likewise.
	* gcc.dg/analyzer/fd-symbolic-socket.c: Likewise.

(cherry picked from commit ce33bbfcbc7dd3afc6c96fb48a19ed00f0c598ce)