[nvptx] Xfail sibcall execution tests

[nvptx] Xfail sibcall execution tests

On nvptx I see the following FAIL:
...
FAIL: gcc.dg/sibcall-3.c execution test
...

The test-case states that "this test is xfailed on targets without sibcall
patterns".

The nvptx port doesn't have a sibcall pattern, so add an xfail.  Likewise in
two similar test-cases.

Tested on nvptx.

gcc/testsuite/ChangeLog:

2022-02-20  Tom de Vries  <tdevries@suse.de>

	* gcc.dg/sibcall-10.c: Xfail execution test for nvptx.
	* gcc.dg/sibcall-3.c: Same.
	* gcc.dg/sibcall-4.c: Same.