Merge liblocale.so into libbe.so.

* Make the locale kit a part of libbe.
* Drop the LocaleBackend kludge used from within libbe (and from
  other places, too) in order to access system catalog strings. 
  This is now done via gSystemCatalog, which is provided and initialized
  by libbe.
* Drop all references to liblocale.so from all Jamfiles.
* Add legacy symlink liblocale.so in order to keep optional packages
  that rely on it in a working state.

TODO: the documentation hasn't been updated.

build/jam/BuildSetup

@@ -477,7 +477,7 @@ HAIKU_SELECT_UNAME_ETC_LIB = ;	# libroot, against which we link anyway
 
 
 # locale libraries
-HAIKU_LOCALE_LIBS = liblocale.so liblocalestub.a ;
+HAIKU_LOCALE_LIBS = liblocalestub.a ;
 
 
 # library and executable glue code
@@ -904,6 +904,7 @@ if ! $(HOST_PLATFORM_BEOS_COMPATIBLE) {
 		[ FDirName $(HAIKU_TOP) headers build os drivers ]
 		[ FDirName $(HAIKU_TOP) headers build os kernel ]
 		[ FDirName $(HAIKU_TOP) headers build os interface ]
+		[ FDirName $(HAIKU_TOP) headers build os locale ]
 		[ FDirName $(HAIKU_TOP) headers build os opengl ]
 		[ FDirName $(HAIKU_TOP) headers build os storage ]
 		[ FDirName $(HAIKU_TOP) headers build os support ]
@@ -1067,7 +1068,7 @@ if ! $(TARGET_PLATFORM_HAIKU_COMPATIBLE) && $(TARGET_PLATFORM_BEOS_COMPATIBLE) {
 if $(TARGET_PLATFORM) = libbe_test {
 	# headers and flags
 	TARGET_HDRS +=
-		[ PublicHeaders $(DOT) app drivers game interface kernel storage
+		[ PublicHeaders $(DOT) app drivers game interface kernel locale storage
 			support ]
 		[ PrivateHeaders $(DOT) ] ;
 	TARGET_DEFINES += __HAIKU__ ;