Optimised passing around of timezone a bit

* _kern_[sg]et_timezone() now accepts/passes out the timezone name, too
* adjust Time preflet and clockconfig to pass the timezone name into the kernel
  when calling _kern_set_timezone()
* ajust implementation of tzset() to fetch the timezone name from the kernel
  via _kern_get_timezone() instead of reading 'libroot_timezone_info'
* the Time preflet no longer writes 'libroot_timezone_info'


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@38164 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/libroot/locale/ICUTimeConversion.h

@@ -8,6 +8,8 @@
 
 #include <time.h>
 
+#include <StorageDefs.h>
+
 #include "ICUTimeData.h"
 #include "LocaleBackend.h"
 
@@ -39,7 +41,7 @@ private:
 
 			TimeConversionDataBridge*	fDataBridge;
 
-			char				fTimeZoneID[64];
+			char				fTimeZoneID[B_FILE_NAME_LENGTH];
 };