move utmp.h include to libbb.h

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

init/halt.c

@@ -74,7 +74,6 @@
 
 #if ENABLE_FEATURE_WTMP
 #include <sys/utsname.h>
-#include <utmp.h>
 
 static void write_wtmp(void)
 {

init/init.c

@@ -115,9 +115,6 @@
 #ifdef __linux__
 #include <linux/vt.h>
 #endif
-#if ENABLE_FEATURE_UTMP
-# include <utmp.h> /* DEAD_PROCESS */
-#endif
 #include "reboot.h" /* reboot() constants */
 
 /* Used only for sanitizing purposes in set_sane_term() below. On systems where