srcu-cbmc: Use /usr/bin/awk instead of /bin/awk

Most OS distribution have awk in /usr/bin not in /bin
Without this patch, kernel-devsrc fails to build as
runtime dependency for srcu-cbmc script /bin/awk is
not found.

Signed-off-by: Kushwaha, Priyalee <priyalee.kushwaha@intel.com>
Acked-by: Lance Roy <ldr709@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

tools/testing/selftests/rcutorture/formal/srcu-cbmc/modify_srcu.awk

@@ -1,4 +1,4 @@
-#!/bin/awk -f
+#!/usr/bin/awk -f
 
 # Modify SRCU for formal verification. The first argument should be srcu.h and
 # the second should be srcu.c. Outputs modified srcu.h and srcu.c into the