add bidi into the build flag and define IBMBID if bidi is set. fix bug 75463. r/sr=sfraser@netscape.com

build/mac/build_scripts/Moz/BuildFlags.pm

@@ -224,6 +224,7 @@ sub SetOptionDefines($)
   $optiondefines->{"lowmem"}{"MOZ_MAC_LOWMEM"} = 1;
   $optiondefines->{"ldap_experimental"}{"MOZ_LDAP_XPCOM_EXPERIMENTAL"} = 1;
   $optiondefines->{"useimg2"}{"USE_IMG2"}     = 1;
+  $optiondefines->{"bidi"}{"IBMBIDI"}     = 1;
 }