targets/xvmc: Add uninstall hooks to handle megadriver hardlinks.

src/gallium/targets/xvmc/Makefile.am

@@ -82,3 +82,8 @@ install-data-hook:
 		       $${dest_dir}/$${k};				\
 	done;								\
 	$(RM) -f $${dest_dir}/libXvMCgallium.*
+
+uninstall-hook:
+	for i in $(TARGET_DRIVERS); do					\
+		$(RM) $(DESTDIR)$(xvmcdir)/libXvMC$${i}.so{,.$(XVMC_MAJOR){,.$(XVMC_MINOR){,.0}}}; \
+	done;