Revert "tests: Don't link mock libraries against libvirt and gnulib"

This reverts commit 6aa90452aa.

Turns out that not linking against libvirt and gnulib is okay for
regular Linux (and FreeBSD) builds, but makes mingw very unhappy.

  .../virnetserverclientmock_la-virnetserverclientmock.o:
    In function `virNetSocketGetSELinuxContext':
    .../virnetserverclientmock.c:61: undefined reference to `rpl_strdup'
  .../libvirportallocatormock_la-virportallocatortest.o:
    In function `init_syms':
    .../virportallocatortest.c:61: undefined reference to `virFileClose'

tests/Makefile.am

@@ -946,6 +946,7 @@ virnetserverclientmock_la_SOURCES = \
 	virnetserverclientmock.c
 virnetserverclientmock_la_CFLAGS = $(AM_CFLAGS)
 virnetserverclientmock_la_LDFLAGS = $(MOCKLIBS_LDFLAGS)
+virnetserverclientmock_la_LIBADD = $(GNULIB_LIBS)
 
 if WITH_GNUTLS
 virnettlscontexttest_SOURCES = \
@@ -1024,6 +1025,7 @@ libvirportallocatormock_la_SOURCES = \
 	virportallocatortest.c
 libvirportallocatormock_la_CFLAGS = $(AM_CFLAGS) -DMOCK_HELPER=1
 libvirportallocatormock_la_LDFLAGS = $(MOCKLIBS_LDFLAGS)
+libvirportallocatormock_la_LIBADD = ../src/libvirt.la
 
 vircgrouptest_SOURCES = \
 	vircgrouptest.c testutils.h testutils.c
@@ -1049,6 +1051,8 @@ virpcitest_LDADD = $(LDADDS)
 virpcimock_la_SOURCES = \
 	virpcimock.c
 virpcimock_la_CFLAGS = $(AM_CFLAGS)
+virpcimock_la_LIBADD = $(GNULIB_LIBS) \
+					   ../src/libvirt.la
 virpcimock_la_LDFLAGS = $(MOCKLIBS_LDFLAGS)
 
 nodeinfomock_la_SOURCES = \
@@ -1064,6 +1068,8 @@ virnetdevtest_LDADD = $(LDADDS)
 virnetdevmock_la_SOURCES = \
 	virnetdevmock.c
 virnetdevmock_la_CFLAGS = $(AM_CFLAGS) $(LIBNL_CFLAGS)
+virnetdevmock_la_LIBADD = $(GNULIB_LIBS) \
+					   ../src/libvirt.la
 virnetdevmock_la_LDFLAGS = $(MOCKLIBS_LDFLAGS)
 
 virrotatingfiletest_SOURCES = \