pstree: new applet. +1664 bytes

   text    data     bss     dec     hex filename
 883379     936   17192  901507   dc183 busybox_old
 885043     936   17192  903171   dc803 busybox_unstripped

Signed-off-by: Lauri Kasanen <curaga@operamail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/include/libbb.h b/include/libbb.h
index 7c1db3f..d3ad6e2 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1426,6 +1426,7 @@
 	char *argv0;
 	char *exe;
 	IF_SELINUX(char *context;)
+	IF_FEATURE_SHOW_THREADS(unsigned main_thread_pid;)
 	/* Everything below must contain no ptrs to malloc'ed data:
 	 * it is memset(0) for each process in procps_scan() */
 	unsigned long vsz, rss; /* we round it to kbytes */