Default to set TZ=UTC0 for RTC plugin

This patch sets the TZ variable to a sane default, UTC.  Fixing, at
least, the time restore problems of the RTC plugin.

Also, let the C library figure out DST, as the docs say -1 does ...

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

plugins/rtc.c

@@ -118,6 +118,7 @@ static void rtc_restore(void *arg)
 	}
 
 	print_desc(NULL, "Restoring system clock (UTC) from RTC");
+	tm.tm_isdst = -1; /* Use tzdata to figure it out, please. */
 	tv.tv_sec = mktime(&tm);
 	if (tv.tv_sec < RTC_TIMESTAMP_BEGIN_2000) {
 		errno = EINVAL;

src/finit.c

@@ -30,6 +30,7 @@
 #include <fstab.h>
 #endif
 #include <mntent.h>
+#include <time.h>		/* tzet() */
 #include <sys/mount.h>
 #include <sys/stat.h>		/* umask(), mkdir() */
 #include <sys/wait.h>
@@ -319,11 +320,14 @@ int main(int argc, char *argv[])
 	ctx = &loop;
 
 	/*
-	 * Set PATH, SHELL, PWD and umask early to something sane
+	 * Set PATH, SHELL, PWD, TZ and umask early to something sane
 	 */
 	setenv("PATH", _PATH_STDPATH, 1);
 	setenv("SHELL", _PATH_BSHELL, 1);
 
+	setenv("TZ", "UTC0", 1);
+	tzset();
+
 	chdir("/");
 	umask(0);