Use bash exec in select_version

- Changed to have select_version call the target program using exec rather
  than just a simple call.  This will cause the select_version process to be
  replaced entirely with the target process.  This makes it easier for using
  jobs to find the process by name (since there will only be one rather than
  two).

Change-Id: Iebdafed6616762ecbed698d1959cbd708006d8f7
Signed-off-by: Michael Walsh <micwalsh@us.ibm.com>
diff --git a/bin/select_version b/bin/select_version
index 320fc59..917c545 100755
--- a/bin/select_version
+++ b/bin/select_version
@@ -106,6 +106,7 @@
   if [ "${1}" == "--print_only" ] ; then
     echo "${target_program_path}"
   else
-    ${target_program_path} "${@}"
+    # Use exec in order to replace this process with the target process.
+    exec ${target_program_path} "${@}"
   fi