[testsuite] Add missing require-effective-target allloca

[testsuite] Add missing require-effective-target allloca

Add missing require-effect-target alloca directives.

Tested on nvptx.

gcc/testsuite/ChangeLog:

	* gcc.dg/torture/pr92088-1.c: Add require-effective-target alloca.
	* gcc.dg/torture/pr92088-2.c: Same.
	* gcc.dg/torture/pr93124.c: Same.
	* gcc.dg/torture/pr94479.c: Same.
	* gcc.dg/tree-ssa/builtin-sprintf-warn-22.c: Same.