Cause clang to emit the definition of a type used only by pointer

Cause clang to emit the definition of a type used only by pointer

gdb/testsuite/
	* gdb.stabs/gdb11479.c (tag_dummy_enum): introduce a variable to cause
	clang to emit the full definition of type required by the test
	* gdb.stabs/gdb11479.exp (do_test): correct a typo in a test message