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/debs/general b/files/debs/general
index d64417f..7e481b4 100644
--- a/files/debs/general
+++ b/files/debs/general
@@ -5,6 +5,7 @@
 curl
 default-jre-headless  # NOPRIME
 g++
+gawk
 gcc
 gettext  # used for compiling message catalogs
 git