kill a bash specific variable substitution in the "configure" script

so that it can be executed by a standard shell
(the section is question is windows specific, so just remove it)
This should fix PR pkg/40765 by Joern Clausen

graphics/graphviz/distinfo

@@ -1,10 +1,10 @@
-$NetBSD: distinfo,v 1.30 2009/02/26 19:45:14 sno Exp $
+$NetBSD: distinfo,v 1.31 2009/02/28 13:19:46 drochner Exp $
 
 SHA1 (graphviz-2.20.3.tar.gz) = 63ae6bdb6b410387477d339225cc4f61c2bc7322
 RMD160 (graphviz-2.20.3.tar.gz) = 64c80f3af55668e487f911132407c332c3c38e87
 Size (graphviz-2.20.3.tar.gz) = 13381532 bytes
 SHA1 (patch-aa) = 6670dcf2d00ee81012b1acbc3bc141f9405c0b30
-SHA1 (patch-ab) = c7d1f59d1bf2483d16d79dbf9ade57e61a98cded
+SHA1 (patch-ab) = 44dfdec30508583afaa1d44d4bda54341290356b
 SHA1 (patch-ag) = 4b89f087ba96d29b92a1b8c46e3ac041039df459
 SHA1 (patch-aj) = 0adc177fb7c3e654cf46560a8c91e2712bc7d16a
 SHA1 (patch-ak) = 91133de18229d2165be392c790a504547a3adf64

graphics/graphviz/patches/patch-ab

@@ -1,6 +1,8 @@
---- configure.orig	2008-10-07 23:54:55.000000000 +0000
-+++ configure	2009-02-26 19:17:53.000000000 +0000
-@@ -2402,18 +2402,26 @@
+$NetBSD: patch-ab,v 1.15 2009/02/28 13:19:46 drochner Exp $
+
+--- configure.orig	2008-10-08 01:54:55.000000000 +0200
++++ configure
+@@ -2402,18 +2402,26 @@ GRAPHVIZ_VERSION_MICRO=3
  
  
  
@@ -39,7 +41,7 @@
  
  
  
-@@ -6457,6 +6465,9 @@
+@@ -6457,6 +6465,9 @@ if test "${GCC}" != "yes" ; then
  	    ;;
  	*-sgi-irix* )
  	    ;;
@@ -49,3 +51,14 @@
      esac
  else
      case "${CC}" in
+@@ -34814,10 +34825,6 @@ fi
+ 
+ 
+ 
+-# Check whether --with-platformsdkincludedir was given.
+-if test "${with_platformsdkincludedir+set}" = set; then
+-  withval=$with_platformsdkincludedir; PLATFORMSDKINCLUDE=$withval; PLATFORMSDKINCLUDE_ESCAPED=${PLATFORMSDKINCLUDE//'\\'/\\\\}; PLATFORMSDKINCLUDE_ESCAPED=${PLATFORMSDKINCLUDE_ESCAPED// /\\ }
+-fi
+ 
+ 
+