Set NATIVE_CC/CC, NATIVE_CXX/CXX, and NATIVE_LD/LD for cross-builds.

The NATIVE_xyz versions are for packages that build tools that they
run natively but don't end up in the final product.

Index: mk/tools/tools.NetBSD.mk
===================================================================
RCS file: /cvsroot/pkgsrc/mk/tools/tools.NetBSD.mk,v
retrieving revision 1.46
diff -p -u -r1.46 tools.NetBSD.mk
--- mk/tools/tools.NetBSD.mk	26 May 2012 13:09:54 -0000	1.46
+++ mk/tools/tools.NetBSD.mk	23 Apr 2013 13:29:19 -0000
@@ -137,7 +137,13 @@ TOOLS_CREATE+=			ar
 TOOLS_PATH.ranlib?=		${TOOLDIR}/bin/${MACHINE_GNU_PLATFORM}-ranlib
 TOOLS_CREATE+=			ranlib
 
-NATIVE_CC:=	/usr/bin/cc
+NATIVE_CC:=	/usr/bin/cc -B /usr/libexec -B /usr/bin
 CC=		${TOOLDIR}/bin/${MACHINE_GNU_PLATFORM}-gcc
 
+NATIVE_CXX:=	/usr/bin/c++ -B /usr/libexec -B /usr/bin
+CXX=		${TOOLDIR}/bin/${MACHINE_GNU_PLATFORM}-g++
+
+NATIVE_LD:=	/usr/bin/ld
+LD=		${TOOLDIR}/bin/${MACHINE_GNU_PLATFORM}-ld
+
 .endif