[gimp] No SYMPREFIX should be used for 64-bit Windows

[Tor Lillqvist <tml src gnome org>]

commit ee7a922cbafe0050e3964a40977ef9170a269fea
Author: Tor Lillqvist <tml iki fi>
Date:   Mon Sep 27 13:22:54 2010 +0300

    No SYMPREFIX should be used for 64-bit Windows
    
    Earlier builds of mingw-w64 misguidedly used the _ prefix, but not
    current ones. Thanks to Fridrich Strba.

 configure.ac |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 830d40c..dd5ff61 100644
--- a/configure.ac
+++ b/configure.ac
@@ -863,7 +863,10 @@ AC_MSG_CHECKING([whether symbols are prefixed])
 
 case "$host_os" in
   mingw*)
-    SYMPREFIX='_'
+    case "$host_cpu" in 
+	  x86_64) SYMPREFIX='' ;;
+	  *) SYMPREFIX='_' ;;
+	esac
     ;;
   darwin* | rhapsody* | machten*)
     SYMPREFIX='_'