msgpack-python requires g++

msgpack-python when installed from source requires a C++ compiler
installed on the system, otherwise it falls back to the python
implementation.

Change-Id: Iffe1f90f3a70780be22459c3f7a3cddfe47f01ca
diff --git a/files/debs/general b/files/debs/general
index 5047c12..84d4302 100644
--- a/files/debs/general
+++ b/files/debs/general
@@ -4,6 +4,7 @@
 wget
 psmisc
 gcc
+g++
 git
 graphviz # testonly - docs
 lsof # useful when debugging