c++: Enable -Walloc-size and -Wcalloc-transposed-args warnings for C++

c++: Enable -Walloc-size and -Wcalloc-transposed-args warnings for C++

The following patch enables the -Walloc-size and -Wcalloc-transposed-args
warnings for C++ as well.

Tracking just 6 arguments for SIZEOF_EXPR for the calloc purposes
is because I see alloc_size 1,2, 2,3 and 3,4 pairs used in the wild,
so we need at least 5 to cover that rather than 3, and don't want to waste
too much compile time/memory for that.

2023-12-21  Jakub Jelinek  <jakub@redhat.com>

gcc/c-family/
	* c.opt (Walloc-size): Enable also for C++ and ObjC++.
gcc/cp/
	* cp-gimplify.cc (cp_genericize_r): If warn_alloc_size, call
	warn_for_alloc_size for -Walloc-size diagnostics.
	* semantics.cc (finish_call_expr): If warn_calloc_transposed_args,
	call warn_for_calloc for -Wcalloc-transposed-args diagnostics.
gcc/testsuite/
	* g++.dg/warn/Walloc-size-1.C: New test.
	* g++.dg/warn/Wcalloc-transposed-args-1.C: New test.