Fix minor errors with Windows ECHO, DEL, MD

- Quotes were not removed by ECHO.
- DEL would print an error on nonexistent file.
- MD would do this plus return a nonzero exit code.

src/Makefile

@@ -315,7 +315,7 @@ WINDRES:=$(WINDRES) $(WINDRESFLAGS)\
 	$(debug_opts) --include-dir=win32 -O coff
 
 %/ :
-	$(.)$(mkdir) $@
+	$(.)$(mkdir) $(call Windows_path,$@)
 
 # this is needed so the target can be referenced in the
 # prerequisites
@@ -385,14 +385,16 @@ $(eval $(call _recipe,o,nas,$(NASM) -o $$@ $$<))
 $(eval $(call _recipe,o,s,$(CC) $(ASFLAGS) -c -o $$@ $$<))
 $(eval $(call _recipe,res,rc,$(WINDRES) -i $$< -o $$@))
 
+_rm=$(.)$(rmrf) $(call Windows_path,$(1))
+
 cleandep :
-	$(.)$(rmrf) $(depends) comptime.h
+	$(call _rm,$(depends) comptime.h)
 
 clean :
-	$(.)$(rmrf) $(exe) $(dbg) $(dbg).txt $(objects)
+	$(call _rm,$(exe) $(dbg) $(dbg).txt $(objects))
 
 distclean :
-	$(.)$(rmrf) ../bin ../objs ../deps comptime.h
+	$(call _rm,../bin ../objs ../deps comptime.h)
 
 info:
 ifdef WINDOWSHELL

src/Makefile.d/platform.mk

@@ -5,11 +5,11 @@
 PKG_CONFIG?=pkg-config
 
 ifdef WINDOWSHELL
-rmrf?=DEL /S /Q
-mkdir?=MD
+rmrf=2>NUL DEL /S /Q
+mkdir=-2>NUL MD
 else
-rmrf?=rm -rf
-mkdir?=mkdir -p
+rmrf=rm -rf
+mkdir=mkdir -p
 endif
 
 ifdef LINUX64

src/Makefile.d/util.mk

@@ -12,6 +12,9 @@ Wildvar=$(foreach v,$(filter $(1),$(.VARIABLES)),$($(v)))
 # directory of the file.
 List=$(addprefix $(dir $(1)),$(file < $(1)))
 
+# Convert path separators to backslash on Windows.
+Windows_path=$(if $(WINDOWSHELL),$(subst /,\,$(1)),$(1))
+
 define Propogate_flags =
 opts+=$$($(1)_CFLAGS)
 libs+=$$($(1)_LDFLAGS)
@@ -73,7 +76,7 @@ Echo_name=
 Print=
 
 ifndef SILENT
-Echo=@echo "$(1)"
+Echo=@echo $(1)
 ifndef ECHO
 ifndef NOECHOFILENAMES
 Echo_name=$(call Echo,-- $(1) ...)