Merge version 6.3.0-18+rpi1 and 6.3.0-18+deb9u1 to produce 6.3.0-18+rpi1+deb9u1

diff --cc debian/changelog
index 635ded4d42b4702528ca9d06929e716c1aba6264,c17fe8615c6cfcc2d187e9f85b64fa5609223b5f..ec9ea4630b497c9f7e8ba01a9100a5c2d0fa73e7
--- 1/debian/changelog
--- 2/debian/changelog
+++ b/debian/changelog
@@@ -1,9 -1,8 +1,15 @@@
- gcc-6 (6.3.0-18+rpi1) stretch-staging; urgency=medium
++gcc-6 (6.3.0-18+rpi1+deb9u1) stretch-staging; urgency=medium
 +
 +  [changes brought forward from 6.1.1-1+rpi1 by Peter Michael Green <plugwash@raspbian.org> at Wed, 11 May 2016 20:56:09 +0000]
 +  * Disable testsuite.
 +
-  -- Raspbian forward porter <root@raspbian.org>  Thu, 01 Jun 2017 13:33:01 +0000
++ -- Raspbian forward porter <root@raspbian.org>  Thu, 01 Mar 2018 00:03:02 +0000
++
+ gcc-6 (6.3.0-18+deb9u1) stretch-security; urgency=medium
+ 
+   * Backport of retpoline support by HJ Lu
+ 
+  -- Moritz Muehlenhoff <jmm@debian.org>  Wed, 14 Feb 2018 17:53:20 +0100
  
  gcc-6 (6.3.0-18) unstable; urgency=medium