$NetBSD$

Remove redundancy of $(SHELL) to avoid an error in installation phase.

--- configure.orig	2011-07-16 11:42:01.000000000 +0000
+++ configure
@@ -2245,7 +2245,7 @@ else
   if test -f "$ac_aux_dir/mkinstalldirs"; then
     mkdir_p='$(mkinstalldirs)'
   else
-    mkdir_p='$(SHELL) $(install_sh) -d'
+    mkdir_p='$(install_sh) -d'
   fi
 fi