library: remove procps_version functions

It doesn't make any sense to have the binary version strings
embedded into the library. The version strings are defined
already either in the Makefile or in include/c.h

pgrep.c

@@ -53,7 +53,6 @@
 #include "proc/sig.h"
 #include "proc/devname.h"
 #include "proc/sysinfo.h"
-#include "proc/version.h" /* procps_version */
 
 static int i_am_pkill = 0;