OpenMP: Constructors and destructors for "declare target" static aggregates: Fix...

OpenMP: Constructors and destructors for "declare target" static aggregates: Fix effective-target keyword in test cases

(Most of) the tests added in commit f1bfba3a9b3f31e3e06bfd1911c9f223869ea03f
"OpenMP: Constructors and destructors for "declare target" static aggregates"
had a mismatch between dump file production and its scanning; the former needs
to use 'offload_target_nvptx' (like 'offload_target_amdgcn'), not
'offload_device_nvptx'.

	libgomp/
	* testsuite/libgomp.c++/static-aggr-constructor-destructor-1.C:
	Fix effective-target keyword.
	* testsuite/libgomp.c++/static-aggr-constructor-destructor-2.C:
	Likewise.
	* testsuite/libgomp.c-c++-common/target-is-initial-host-2.c:
	Likewise.
	* testsuite/libgomp.c-c++-common/target-is-initial-host.c:
	Likewise.
	* testsuite/libgomp.fortran/target-is-initial-host-2.f90:
	Likewise.
	* testsuite/libgomp.fortran/target-is-initial-host.f: Likewise.
	* testsuite/libgomp.fortran/target-is-initial-host.f90: Likewise.

(cherry picked from commit 9f5d22e3e2b8e4532896a4f3837cb86006d5930c)