libxl: test programs: Fix make race re libxenlight.so

The test programs were getting the proper libxenlight.so on their link
line.  Filter it out.  Also change the soname of the test library to
match the real one, so that libxutil is satisfied with it.

Reported-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Olaf Hering <olaf@aepfle.de>
Cc: Ian Campbell <Ian.Campbell@citrix.com>

tools/libxl/Makefile

@@ -195,7 +195,7 @@ libxenlight.so.$(MAJOR).$(MINOR): $(LIBXL_OBJS)
 	$(CC) $(LDFLAGS) -Wl,$(SONAME_LDFLAG) -Wl,libxenlight.so.$(MAJOR) $(SHLIB_LDFLAGS) -o $@ $^ $(LIBXL_LIBS) $(APPEND_LDFLAGS)
 
 libxenlight_test.so: $(LIBXL_OBJS) $(LIBXL_TEST_OBJS)
-	$(CC) $(LDFLAGS) -Wl,$(SONAME_LDFLAG) -Wl,libxenlight_test.so $(SHLIB_LDFLAGS) -o $@ $^ $(LIBXL_LIBS) $(APPEND_LDFLAGS)
+	$(CC) $(LDFLAGS) -Wl,$(SONAME_LDFLAG) -Wl,libxenlight.so.$(MAJOR) $(SHLIB_LDFLAGS) -o $@ $^ $(LIBXL_LIBS) $(APPEND_LDFLAGS)
 
 libxenlight.a: $(LIBXL_OBJS)
 	$(AR) rcs libxenlight.a $^
@@ -216,7 +216,7 @@ xl: $(XL_OBJS) libxlutil.so libxenlight.so
 	$(CC) $(LDFLAGS) -o $@ $(XL_OBJS) libxlutil.so $(LDLIBS_libxenlight) $(LDLIBS_libxenctrl) -lyajl $(APPEND_LDFLAGS)
 
 test_%: test_%.o test_common.o libxlutil.so libxenlight_test.so
-	$(CC) $(LDFLAGS) -o $@ $^ $(LDLIBS_libxenlight) $(LDLIBS_libxenctrl) -lyajl $(APPEND_LDFLAGS)
+	$(CC) $(LDFLAGS) -o $@ $^ $(filter-out %libxenlight.so, $(LDLIBS_libxenlight)) $(LDLIBS_libxenctrl) -lyajl $(APPEND_LDFLAGS)
 
 libxl-save-helper: $(SAVE_HELPER_OBJS) libxenlight.so
 	$(CC) $(LDFLAGS) -o $@ $(SAVE_HELPER_OBJS) $(LDLIBS_libxenctrl) $(LDLIBS_libxenguest) $(APPEND_LDFLAGS)