Use os.arch on 64 bit builds.

Index: platform_build/bsd_ant/build.xml
--- platform_build/bsd_ant/build.xml.orig
+++ platform_build/bsd_ant/build.xml
@@ -5,7 +5,7 @@
 	<property name="libname32" value="liblwjgl.so"/>
 	<property name="libname64" value="liblwjgl64.so"/>
 	<property name="libs32" value="-L/usr/X11R6/lib -L/usr/local/lib -lm -lX11 -lXext -lXcursor -lXrandr -pthread -L${java.home}/lib/i386 -ljawt" />
-	<property name="libs64" value="-L/usr/X11R6/lib -L/usr/local/lib -lm -lX11 -lXext -lXcursor -lXrandr -lXxf86vm -pthread -L${java.home}/lib/amd64 -ljawt" />
+	<property name="libs64" value="-L/usr/X11R6/lib -L/usr/local/lib -lm -lX11 -lXext -lXcursor -lXrandr -lXxf86vm -pthread -L${java.home}/lib/${os.arch} -ljawt" />
     <property name="cflags32" value="-O2 -Wall -c -fPIC -std=c99 -Wunused"/>
 
 	<target name="clean">
@@ -67,7 +67,9 @@
     	<condition property="build.64bit.only">
             <and>
                 <os name="OpenBSD"/>
-                <equals arg1="${hwplatform}" arg2="amd64"/>
+                <not>
+                    <equals arg1="${hwplatform}" arg2="i386"/>
+                </not>
             </and>
         </condition>
 
