build: Add 'clean' target to Makefile.win32 build system

The Makefile.win32 in the subdirectories provide a working 'clean'
target (defined in Makefile.win32.common), the central Makefile.win32
'clean' target does not do anything.

Replace the noop 'clean' target with one that cleans all the subdirs.

Makefile.am

@@ -5,6 +5,7 @@ EXTRA_DIST += \
 	README.win32 \
 	Makefile.win32 \
 	build/Makefile.win32.common \
+	build/Makefile.win32.inform \
 	build/Makefile.win32.features \
 	build/Makefile.win32.features-h \
 	$(NULL)

Makefile.win32

@@ -2,7 +2,7 @@
 # Edit build/Makefile.win32.common for customization
 
 top_srcdir = .
-include $(top_srcdir)/build/Makefile.win32.common
+include $(top_srcdir)/build/Makefile.win32.inform
 
 all: cairo
 
@@ -14,3 +14,9 @@ perf: inform
 
 test: inform
 	@$(MAKE) -C test -f Makefile.win32 test
+
+clean:
+	@$(MAKE) -C boilerplate -f Makefile.win32 clean
+	@$(MAKE) -C perf -f Makefile.win32 clean
+	@$(MAKE) -C src -f Makefile.win32 clean
+	@$(MAKE) -C test -f Makefile.win32 clean

build/Makefile.win32.common

@@ -3,6 +3,7 @@ default: all
 #
 # Edit build/Makefile.win32.features to enable features to build
 #
+include $(top_srcdir)/build/Makefile.win32.inform
 include $(top_srcdir)/build/Makefile.win32.features
 include $(top_srcdir)/build/Makefile.win32.features-h
 
@@ -48,20 +49,6 @@ DEFAULT_ARFLAGS = -nologo
 CAIRO_LDFLAGS = $(DEFAULT_LDFLAGS) $(LDFLAGS)
 CAIRO_ARFLAGS = $(DEFAULT_ARFLAGS) $(LDFLAGS)
 
-inform:
-	@echo
-ifneq ($(CFG),release)
-ifneq ($(CFG),debug)
-	@echo "Invalid configuration "$(CFG)" specified."
-	@echo -n "You must specify a configuration when "
-	@echo "running make, e.g. make CFG=debug"
-	@echo
-	@echo -n "Possible choices for configuration are "
-	@echo "'release' and 'debug'"
-	@exit 1
-endif
-endif
-
 # Some generic rules
 
 $(CFG)/%.obj: %.c $(top_srcdir)/src/cairo-features.h

build/Makefile.win32.inform

@@ -0,0 +1,13 @@
+inform:
+	@echo
+ifneq ($(CFG),release)
+ifneq ($(CFG),debug)
+	@echo "Invalid configuration "$(CFG)" specified."
+	@echo -n "You must specify a configuration when "
+	@echo "running make, e.g. make CFG=debug"
+	@echo
+	@echo -n "Possible choices for configuration are "
+	@echo "'release' and 'debug'"
+	@exit 1
+endif
+endif