skill: Remove unrequired headers

Removed unrequired headers in the include statements for skill.

skill.c

@@ -43,9 +43,6 @@
 #include "xalloc.h"
 #include "proc/pwcache.h"
 #include "proc/devname.h"
-#include "proc/procps.h"    /* char *user_from_uid(uid_t uid) */
-#include "proc/readproc.h"
-#include "proc/version.h"    /* procps_version */
 #include "rpmatch.h"
 
 #define DEFAULT_NICE 4