Fix cross-build of pkgtools/pkg_install.

Can't execute the newly built tools if they were cross-built.

Index: pkgtools/pkg_install/Makefile
===================================================================
RCS file: /cvsroot/pkgsrc/pkgtools/pkg_install/Makefile,v
retrieving revision 1.194
diff -p -u -r1.194 Makefile
--- pkgtools/pkg_install/Makefile	8 Apr 2013 11:17:20 -0000	1.194
+++ pkgtools/pkg_install/Makefile	23 Apr 2013 13:29:20 -0000
@@ -42,7 +42,10 @@ CHECK_PERMS=		no
 # pkg_install.
 #
 # We also use the newly built pkg_{add,create,delete} since upgrading
-# from an older pkg_install might required features of the new program.
+# from an older pkg_install might required features of the new
+# program, provided that we are not cross-compiling.  (XXX If we are
+# cross-compiling, we should maybe have a host build dependency on
+# ourselves...)
 #
 # Note that the definitions are only overriden for the phases that are
 # supposed to use them.  pkg_admin pmatch might be used when looking for
@@ -50,7 +53,7 @@ CHECK_PERMS=		no
 # be rethought.
 USE_NATIVE_GCC=		yes
 
-.if defined(_PKGSRC_BARRIER)
+.if defined(_PKGSRC_BARRIER) && empty(USE_CROSS_COMPILE:M[yY][eE][sS])
 PKG_ADD_CMD=		${WRKSRC}/add/pkg_add
 PKG_CREATE_CMD=		${WRKSRC}/create/pkg_create
 PKG_DELETE_CMD=		${WRKSRC}/delete/pkg_delete