Fix cleaning buildinfo files

We were applying $(wildcard ...) to the literal string
libraries/%/*.buildinfo, which of course had no matches.

ghc.mk

@@ -1151,7 +1151,7 @@ clean_libraries: $(patsubst %,clean_libraries/%_dist-boot,$(PACKAGES_STAGE0))
 
 clean_libraries:
 	$(call removeTrees,$(patsubst %, libraries/%/dist, $(PACKAGES_STAGE1) $(PACKAGES_STAGE2)))
-	$(call removeFiles,$(patsubst %, $(wildcard libraries/%/*.buildinfo), $(PACKAGES_STAGE1) $(PACKAGES_STAGE2)))
+	$(call removeFiles,$(wildcard $(patsubst %, libraries/%/*.buildinfo, $(PACKAGES_STAGE1) $(PACKAGES_STAGE2))))
 
 # We have to define a clean target for each library manually, because the
 # libraries/*/ghc.mk files are not included when we're cleaning.