Made some progress with consolidation of timezone-related code:

* renamed syscalls _kern_[gs]et_tzfilename 
  to _kern_[gs]et_real_time_clock_is_gmt, as the filename part is no longer
  relevant (and the two corresponding parameters were removed)
* C++-ified and reworked clockconfig to use the info from 'Time settings' 
  to setup the timezone info during boot
* removed invocation of _kern_get_tzfilename() from tzset(), as the syscall
  no longer exists and tzset() is currently broken anyway
* adjusted the Time preflet to use the renamed syscall when getting/setting 
  the RTC info


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@37881 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/real_time_clock.h

@@ -42,8 +42,8 @@ bigtime_t _user_system_time(void);
 status_t _user_set_real_time_clock(uint32 time);
 status_t _user_set_timezone(int32 timezoneOffset, bool daylightSavingTime);
 status_t _user_get_timezone(int32 *_timezoneOffset, bool *_daylightSavingTime);
-status_t _user_set_tzfilename(const char* filename, size_t length, bool isGMT);
-status_t _user_get_tzfilename(char *filename, size_t length, bool *_isGMT);
+status_t _user_set_real_time_clock_is_gmt(bool isGMT);
+status_t _user_get_real_time_clock_is_gmt(bool *_isGMT);
 
 #ifdef __cplusplus
 }

headers/private/system/syscalls.h

@@ -367,10 +367,8 @@ extern status_t		_kern_set_timezone(int32 timezoneOffset,
 						bool daylightSavingTime);
 extern status_t		_kern_get_timezone(int32 *_timezoneOffset,
 						bool *_daylightSavingTime);
-extern status_t		_kern_set_tzfilename(const char *filename, size_t length,
-						bool isGMT);
-extern status_t		_kern_get_tzfilename(char *filename, size_t length,
-						bool *_isGMT);
+extern status_t		_kern_set_real_time_clock_is_gmt(bool isGMT);
+extern status_t		_kern_get_real_time_clock_is_gmt(bool *_isGMT);
 
 extern bigtime_t	_kern_system_time();
 extern status_t		_kern_snooze_etc(bigtime_t time, int timebase, int32 flags);