Fortran: Use OpenACC's acc_on_device builtin, fix OpenMP'...

Fortran: Use OpenACC's acc_on_device builtin, fix OpenMP' __builtin_is_initial_device: Harmonize 'libgomp.oacc-fortran/acc_on_device-1-*'

The test case 'libgomp.oacc-fortran/acc_on_device-1-1.f90' added in
commit 3269a722
"Fortran: Use OpenACC's acc_on_device builtin, fix OpenMP' __builtin_is_initial_device"
was missing '-fno-builtin-acc_on_device', and all
'libgomp.oacc-fortran/acc_on_device-1-*' need comments, why that option is
specified.

	PR testsuite/82250
	libgomp/
	* testsuite/libgomp.oacc-fortran/acc_on_device-1-1.f90: Add
	'-fno-builtin-acc_on_device'.
	* testsuite/libgomp.oacc-fortran/acc_on_device-1-2.f: Comment.
	* testsuite/libgomp.oacc-fortran/acc_on_device-1-3.f: Comment.

libgomp/testsuite/libgomp.oacc-fortran/acc_on_device-1-1.f90

 ! { dg-do run }
 ! { dg-additional-options "-cpp" }
 
+! Disable the acc_on_device builtin; we want to test the libgomp library function.
+! { dg-additional-options -fno-builtin-acc_on_device }
+
 ! { dg-additional-options "-fopt-info-all-omp" }
 ! { dg-additional-options "--param=openacc-privatization=noisy" }
 ! { dg-additional-options "-foffload=-fopt-info-all-omp" }

libgomp/testsuite/libgomp.oacc-fortran/acc_on_device-1-2.f

 ! { dg-do run }
-! { dg-additional-options "-cpp -fno-builtin-acc_on_device" }
+! { dg-additional-options "-cpp" }
+
+! Disable the acc_on_device builtin; we want to test the libgomp library function.
+! { dg-additional-options -fno-builtin-acc_on_device }
 
 ! { dg-additional-options "-fopt-info-all-omp" }
 ! { dg-additional-options "--param=openacc-privatization=noisy" }

libgomp/testsuite/libgomp.oacc-fortran/acc_on_device-1-3.f

 ! { dg-do run }
-! { dg-additional-options "-cpp -fno-builtin-acc_on_device" }
+! { dg-additional-options "-cpp" }
+
+! Disable the acc_on_device builtin; we want to test the libgomp library function.
+! { dg-additional-options -fno-builtin-acc_on_device }
 
 ! { dg-additional-options "-fopt-info-all-omp" }
 ! { dg-additional-options "--param=openacc-privatization=noisy" }