libgomp.{c,fortran}/interop-{hip,cuda}: Fix dg-run target selection

libgomp.{c,fortran}/interop-{hip,cuda}: Fix dg-run target selection

While the tests checked whether the CUDA/HIP runtime is available
before processing them, the execution was then done unconditionally,
leading to FAIL when the default device was the host (or the wrong
offload device).

Now the test is only executed ('run') when the default device is an
Nvidia or AMD GPU (depending on the test case, cf. the test file name).
Otherwise, only a 'link' test is done. (Except when the effective-target
check cannot find the runtime lib - then the test is skipped [as before].)

Note: The cublas/hipblas tests use variant functions and iterate over
all devices, such that the cublas or hipblas, respectively, is only
called when the active device is an AMD or Nvidia device, respectively,
while for the host and other device types the fallback is called.

libgomp/ChangeLog:

	* testsuite/libgomp.c/interop-cuda-full.c: Use 'link' instead
	of 'run' when the default device is "! offload_device_nvptx".
	* testsuite/libgomp.c/interop-cuda-libonly.c: Likewise.
	* testsuite/libgomp.c/interop-hip-nvidia-full.c: Likewise.
	* testsuite/libgomp.c/interop-hip-nvidia-no-headers.c: Likewise.
	* testsuite/libgomp.c/interop-hip-nvidia-no-hip-header.c: Likewise.
	* testsuite/libgomp.fortran/interop-hip-nvidia-full.F90: Likewise.
	* testsuite/libgomp.fortran/interop-hip-nvidia-no-module.F90: Likewise.
	* testsuite/libgomp.c/interop-hip-amd-full.c: Use 'link' instead
	of 'run' when the default device is "! offload_device_gcn".
	* testsuite/libgomp.c/interop-hip-amd-no-hip-header.c: Likewise.
	* testsuite/libgomp.fortran/interop-hip-amd-full.F90: Likewise.
	* testsuite/libgomp.fortran/interop-hip-amd-no-module.F90: Likewise.