Fix PR other/91396 static linke error with -fvtable-verify

Fix PR other/91396 static linke error with -fvtable-verify

Fix a bug where linking with -fvtable-verify  and
-static causes the linker to complain about multiple definitions of
things in the vtv_end*.o files (once from the .o file and once from
libvtv.a).

2019-08-12  Caroline Tice  <cmtice@google.com>

        PR other/91396
        * config/gnu-user.h (GNU_USER_TARGET_ENDFILE_SPEC): Only add the
        vtv_end.o or vtv_end_preinit.o files if !static.

From-SVN: r274386