PR ld/19803
* ldlang.c (lang_add_gc_name): New function. Adds the provided
symbol name to the list of gc symbols.
(lang_process): Call lang_add_gc_name with entry_symbol_default if
entry_symbol.name is NULL. Use lang_add_gc_name to add the init
and fini function names.
* pe-dll.c (process_def_file_and_drectve): Add exported names to
the gc symbol list.
* testsuite/ld-pe/pr19803.s: Do not export _testval symbol.
* testsuite/ld-pe/pr19803.d: Tweak expected output.
