Make MOZ_UI_LOCALE available to the build system, merge from aviary branch. See bug 271324

config/autoconf.mk.in

@@ -130,6 +130,11 @@ MOZ_PROFILESHARING = @MOZ_PROFILESHARING@
 MOZ_PROFILELOCKING = @MOZ_PROFILELOCKING@
 MOZ_STORAGE = @MOZ_STORAGE@
 
+# The MOZ_UI_LOCALE var is used to build a particular locale. Do *not*
+# use the var to change any binary files. Do *not* use this var unless you
+# write rules for the "clean-locale" and "locale" targets.
+MOZ_UI_LOCALE = @MOZ_UI_LOCALE@
+
 MOZ_COMPONENTS_VERSION_SCRIPT_LDFLAGS = @MOZ_COMPONENTS_VERSION_SCRIPT_LDFLAGS@
 MOZ_COMPONENT_NSPR_LIBS=@MOZ_COMPONENT_NSPR_LIBS@
 MOZ_COMPONENT_XPCOM_LIBS=@MOZ_COMPONENT_XPCOM_LIBS@

configure.in

@@ -3536,6 +3536,18 @@ dnl =
 dnl ========================================================
 MOZ_ARG_HEADER(Components and Features)
 
+dnl ========================================================
+dnl = Localization
+dnl ========================================================
+
+MOZ_UI_LOCALE=en-US
+
+MOZ_ARG_ENABLE_STRING(ui-locale,
+[  --enable-ui-locale=ab-CD
+                          Select the user interface locale (default: en-US)],
+    MOZ_UI_LOCALE=$enableval )
+AC_SUBST(MOZ_UI_LOCALE)
+
 dnl =========================================================
 dnl = Calendar client
 dnl =========================================================