analyzer: don't use <setjmp.h> in tests [PR97394]

analyzer: don't use <setjmp.h> in tests [PR97394]

PR analyzer/97394 reports issues with analyzer setjmp results
when testing against MUSL.  This patch fixes up gcc.dg/analyzer
so that it doesn't use <setjmp.h>.

gcc/testsuite/ChangeLog:
	PR analyzer/97394
	* gcc.dg/analyzer/setjmp-pr93378.c: Use test-setjmp.h rather than
	<setjmp.h>.
	* gcc.dg/analyzer/sigsetjmp-5.c: Likewise.
	* gcc.dg/analyzer/sigsetjmp-6.c: Likewise.
	* gcc.dg/analyzer/test-setjmp.h: Don't include <setjmp.h>.
	Provide decls of jmp_buf, sigjmp_buf, setjmp, sigsetjmp,
	longjmp, and siglongjmp.