Move gawk into general for post-config

Devstack script for setting post-config needs gawk.
So this patch moves gawk from files/*/nova into files/*/general.

Closes-Bug: #1909041
Change-Id: I06a1a5524f146a8d7337963e846b5a6b7561be13
diff --git a/files/rpms/general b/files/rpms/general
index cfcd7ff..33da0a5 100644
--- a/files/rpms/general
+++ b/files/rpms/general
@@ -1,6 +1,7 @@
 bc
 curl
 dbus
+gawk
 gcc
 gcc-c++
 gettext  # used for compiling message catalogs