Restore 'libgomp.oacc-c-c++-common/nvptx-sese-1.c' SESE regions checking [PR107195, PR107344]

That is, adjust for optimization introduced with recent
commit r13-3217-gc4d15dddf6b9eacb36f535807ad2ee364af46e04
"[PR107195] Set range to zero when nonzero mask is 0", where GCC now
understands that after 'r *= 2;', 'r & 1' will never hold here, and thus
transforms/optimizes/"disturbs" the original code such that GCC/nvptx's later
"Neuter whole SESE regions" optimization no longer is applicable to it:

    UNSUPPORTED: libgomp.oacc-c/../libgomp.oacc-c-c++-common/nvptx-sese-1.c -DACC_DEVICE_TYPE_nvidia=1 -DACC_MEM_SHARED=0 -foffload=nvptx-none  -O0
    PASS: libgomp.oacc-c/../libgomp.oacc-c-c++-common/nvptx-sese-1.c -DACC_DEVICE_TYPE_nvidia=1 -DACC_MEM_SHARED=0 -foffload=nvptx-none  -O2  (test for excess errors)
    PASS: libgomp.oacc-c/../libgomp.oacc-c-c++-common/nvptx-sese-1.c -DACC_DEVICE_TYPE_nvidia=1 -DACC_MEM_SHARED=0 -foffload=nvptx-none  -O2  execution test
    [-PASS:-]{+FAIL:+} libgomp.oacc-c/../libgomp.oacc-c-c++-common/nvptx-sese-1.c -DACC_DEVICE_TYPE_nvidia=1 -DACC_MEM_SHARED=0 -foffload=nvptx-none  -O2   scan-nvptx-none-offload-rtl-dump mach "SESE regions:.* [0-9]+{[0-9]+->[0-9]+(\\.[0-9]+)+}"

Same for C++.

It's unclear to me if this is an actual "problem", which optimization is "more
important", so I've filed PR107344 "GCC/nvptx SESE region optimization" to
capture this question, and here restore what we intend to be testing (to my
understanding) in 'libgomp.oacc-c-c++-common/nvptx-sese-1.c'.

	PR tree-optimization/107195
	PR target/107344
	libgomp/
	* testsuite/libgomp.oacc-c-c++-common/nvptx-sese-1.c: Restore SESE
	regions checking.

libgomp/testsuite/libgomp.oacc-c-c++-common/nvptx-sese-1.c

@@ -22,7 +22,7 @@ int main ()
     if (foo (r))
       r *= 2;
 
-    if (r & 1) /* to here. */
+    if (r & 8) /* to here. */
 #pragma acc loop vector reduction (+:r)
       for (int i = 00; i < 40; i++)
 	r += i;