Fix undefined reference to `libintl_dgettext` on musl
Bug: https://bugs.gentoo.org/832573
Upstream: https://github.com/linux-pam/linux-pam/pull/433

--- a/libpam/Makefile.am
+++ b/libpam/Makefile.am
@@ -21,7 +21,7 @@ noinst_HEADERS = pam_prelude.h pam_private.h pam_tokens.h \
 		include/pam_inline.h include/test_assert.h
 
 libpam_la_LDFLAGS = -no-undefined -version-info 85:1:85
-libpam_la_LIBADD = @LIBAUDIT@ $(LIBPRELUDE_LIBS) $(ECONF_LIBS) @LIBDL@
+libpam_la_LIBADD = @LIBAUDIT@ $(LIBPRELUDE_LIBS) $(ECONF_LIBS) @LIBDL@ @LTLIBINTL@
 
 if HAVE_VERSIONING
   libpam_la_LDFLAGS += -Wl,--version-script=$(srcdir)/libpam.map