configury: add -Zargs-resp to LDFLAGS on OS/2. -Zargs-resp enables a response file support on OS/2. * configure.ac (OS2_LDFLAGS): Add -Zargs-resp on *-*-os2*. * Makefile.am (AM_LDFLAGS): Add OS2_LDFLAGS. Signed-off-by: Gary V. Vaughan <gary@gnu.org>