Makefile: Fix in-tree clean/distclean

Doing 'make clean' or 'make distclean' in a freshly cloned tree results in:

make: *** No rule to make target 'ninja-clean', needed by 'clean'.  Stop.

Make the fallback rules global. While here, change the ninjatool recipe to
always have a zero exit status and thus prevent make to emit a warning.

Fixes: a56650518f ("configure: integrate Meson in the build system")
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <159897001659.442705.15538955005543395950.stgit@bahia.lan>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Makefile

@@ -54,13 +54,6 @@ export NINJA=./ninjatool
 # enough to prime the rest of the build.
 ninjatool: build.ninja
 
-# Only needed in case Makefile.ninja does not exist.
-.PHONY: ninja-clean ninja-distclean clean-ctlist
-clean-ctlist:
-ninja-clean::
-ninja-distclean::
-build.ninja: config-host.mak
-
 Makefile.ninja: build.ninja ninjatool
 	./ninjatool -t ninja2make --omit clean dist uninstall cscope TAGS ctags < $< > $@
 -include Makefile.ninja
@@ -115,6 +108,13 @@ ifneq ($(filter-out $(UNCHECKED_GOALS),$(MAKECMDGOALS)),$(if $(MAKECMDGOALS),,fa
 endif
 endif
 
+# Only needed in case Makefile.ninja does not exist.
+.PHONY: ninja-clean ninja-distclean clean-ctlist
+clean-ctlist:
+ninja-clean::
+ninja-distclean::
+build.ninja: config-host.mak
+
 include $(SRC_PATH)/rules.mak
 
 # lor is defined in rules.mak
@@ -195,7 +195,7 @@ recurse-clean: $(addsuffix /clean, $(ROM_DIRS))
 ######################################################################
 
 clean: recurse-clean ninja-clean clean-ctlist
-	-test -f ninjatool && ./ninjatool $(if $(V),-v,) -t clean
+	if test -f ninjatool; then ./ninjatool $(if $(V),-v,) -t clean; fi
 # avoid old build problems by removing potentially incorrect old files
 	rm -f config.mak op-i386.h opc-i386.h gen-op-i386.h op-arm.h opc-arm.h gen-op-arm.h
 	find . \( -name '*.so' -o -name '*.dll' -o -name '*.[oda]' \) -type f \