analyzer: stricter handling of non-pure builtins [PR96798]

analyzer: stricter handling of non-pure builtins [PR96798]

Amongst other things PR analyzer/96798 notes that
region_model::on_call_pre treats any builtin that hasn't been coded
yet as a no-op (albeit with an unknown return value), which is wrong
for non-pure builtins.

This patch updates that function's handling of such builtins so that it
instead conservatively assumes that any escaped/reachable regions can
be affected by the call, and implements enough handling of specific
builtins to avoid regressing the testsuite (I hope).

gcc/analyzer/ChangeLog:
	PR analyzer/96798
	* region-model-impl-calls.cc (region_model::impl_call_memcpy):
	New.
	(region_model::impl_call_strcpy): New.
	* region-model.cc (region_model::on_call_pre): Flag unhandled
	builtins that are non-pure as having unknown side-effects.
	Implement BUILT_IN_MEMCPY, BUILT_IN_MEMCPY_CHK, BUILT_IN_STRCPY,
	BUILT_IN_STRCPY_CHK, BUILT_IN_FPRINTF, BUILT_IN_FPRINTF_UNLOCKED,
	BUILT_IN_PUTC, BUILT_IN_PUTC_UNLOCKED, BUILT_IN_FPUTC,
	BUILT_IN_FPUTC_UNLOCKED, BUILT_IN_FPUTS, BUILT_IN_FPUTS_UNLOCKED,
	BUILT_IN_FWRITE, BUILT_IN_FWRITE_UNLOCKED, BUILT_IN_PRINTF,
	BUILT_IN_PRINTF_UNLOCKED, BUILT_IN_PUTCHAR,
	BUILT_IN_PUTCHAR_UNLOCKED, BUILT_IN_PUTS, BUILT_IN_PUTS_UNLOCKED,
	BUILT_IN_VFPRINTF, BUILT_IN_VPRINTF.
	* region-model.h (region_model::impl_call_memcpy): New decl.
	(region_model::impl_call_strcpy): New decl.

gcc/testsuite/ChangeLog:
	PR analyzer/96798
	* gcc.dg/analyzer/memcpy-1.c: New test.
	* gcc.dg/analyzer/strcpy-1.c: New test.