don't cp on windows

svn path=/trunk/mcs/; revision=9288

mcs/nant/makefile

@@ -1,9 +1,9 @@
 all: nant.exe
 linux: nant.exe
+	-cp NAnt.exe nant.exe
 windows: nant.exe
 
 nant.exe: NAnt.exe
-	-cp NAnt.exe nant.exe
 
 NAnt.exe: makefile src/*.cs src/Attributes/*.cs src/Tasks/*.cs src/Util/*.cs
 	csc /out:NAnt.exe /recurse:*.cs 
@@ -12,4 +12,4 @@ NAnt_mono.exe: makefile
 	csc /out:NAnt_mono.exe /nostdlib /noconfig /recurse:*.cs /lib:../class/lib /r:corlib.dll /r:System.Xml.dll /r:System.dll /nowarn:1595
 
 clean:
-	rm -f NAnt_mono.exe
+	rm -f NAnt_mono.exe