openwcom.mak: use internal commands if possible

Signed-off-by: KO Myung-Hun <[email protected]>

Author: komh

Mkfiles/openwcom.mak

@@ -34,9 +34,9 @@ RUNPERL         = $(PERL) $(PERLFLAGS)
 .BEFORE
 	set COPYCMD=/y
 
-RM_F		= -del /f
+RM_F		= -rm -f
 LN_S		= copy
-EMPTY		= copy nul:
+EMPTY		= %create
 SIDE		= %null Created by side effect
 
 MAKENSIS        = makensis