d: Only test with default permutation flags for runnable tests.

d: Only test with default permutation flags for runnable tests.

Unless the test explicitly requests, all compilable tests as well as
fail_compilation tests will be ran without any extra flags.

The C++ tests now are checked against shared D runtime library.

gcc/testsuite/ChangeLog:

	* lib/gdc-utils.exp (gdc-convert-test): Handle LINK directive.
	Set PERMUTE_ARGS as DEFAULT_DFLAGS only for runnable tests.
	(gdc-do-test): Set default action of compilable tests to compile.
	Test SHARED_OPTION on runnable_cxx tests.