Add special rules for MinGW

Some (all?) variants of MinGW do not have a working 'fmt'.
This is not indispensable to the rule working, it makes it just look good.

The sed -e 's/\\\\...' rule appears necessary when executing the
command within 'make'. This is definitely a bug. If I execute the
command within the Windows CMD, I need the extra \\. If I execute the
command within bash or sh, I do not.

config.mingw.mk

@@ -28,6 +28,11 @@ OS_NAME_mingw=windows
 
 include $(BUILD)config.gnu.mk
 
+# We need a special treatment of this on Windows
+POSTPROCESS_DEPENDENCY=                             		\
+    ( sed -e 's/.*://' -e 's/\\$$//' < $@ |         		\
+      sed -e 's/^ *//' -e 's/$$/:/' -e 's/\\\\:$$/:/' >> $@ )
+
 # Windows overrides for extensions
 EXE_EXT=        .exe
 LIB_EXT=        .lib

rules.mk

@@ -320,6 +320,7 @@ OBJ_DEPS=$(OBJDIR_DEPS) $(MAKEFILE_DEPS) | hello prebuild
 # http://scottmcpeak.com/autodepend/autodepend.html
 POSTPROCESS_DEPENDENCY=                             \
     ( sed -e 's/.*://' -e 's/\\$$//' < $@ |         \
+      fmt -1 |                                      \
       sed -e 's/^ *//' -e 's/$$/:/' >> $@ )
 
 $(OBJDIR)/%.c$(OBJ_EXT).d:		%.c		$(OBJ_DEPS)