Update Trac ticket URLs to point to GitLab

This moves all URL references to Trac tickets to their corresponding
GitLab counterparts.
15 jobs for master in 359 minutes and 48 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Lint
passed #44438
lint
ghc-linters

00:00:16

 
  Build
passed #44440
x86_64-linux
hadrian-ghc-in-ghci

00:16:04

passed #44439
x86_64-linux
validate-x86_64-linux-deb8-hadrian

02:46:58

passed #44441
x86_64-linux
validate-x86_64-linux-deb9

01:41:02

passed #44442
x86_64-linux
validate-x86_64-linux-deb9-debug

01:10:42

 
  Full Build
failed #44444
aarch64-linux allowed to fail
validate-aarch64-linux-deb9

03:12:00

passed #44445
x86_64-linux
validate-i386-linux-deb9

01:34:17

passed #44443
x86_64-darwin
validate-x86_64-darwin

00:58:18

passed #44447
x86_64-linux
validate-x86_64-linux-deb9-integer-simple

01:07:01

passed #44446
x86_64-linux
validate-x86_64-linux-deb9-llvm

02:23:07

passed #44448
x86_64-linux
validate-x86_64-linux-deb9-unreg

02:21:27

failed #44450
x86_64-windows allowed to fail
validate-x86_64-windows

00:30:06

passed #44449
x86_64-windows
validate-x86_64-windows-hadrian

01:32:29

 
  Cleanup
passed #44452
x86_64-darwin
cleanup-darwin

00:00:05

passed #44451
x86_64-windows
cleanup-windows

00:00:24

 
Name Stage Failure
failed
validate-aarch64-linux-deb9 Full Build
$ cp -Rf $HOME/.cabal cabal-cache
Uploading artifacts...
ghc.tar.xz: found 1 matching files
junit.xml: found 1 matching files

Uploading artifacts to coordinator... ok
id=44444 responseStatus=201 Created token=LKPT6CWk
Uploading artifacts...
junit.xml: found 1 matching files

Uploading artifacts to coordinator... ok
id=44444 responseStatus=201 Created token=LKPT6CWk
ERROR: Job failed: exit code 1
failed
validate-x86_64-windows Full Build
Runtime platform                                    arch=amd64 os=windows pid=3196 revision=7f00c780 version=11.5.1
WARNING: ghc.tar.xz: no matching files
WARNING: junit.xml: no matching files
ERROR: No files to upload
Uploading artifacts...
Runtime platform
arch=amd64 os=windows pid=2672 revision=7f00c780 version=11.5.1
WARNING: junit.xml: no matching files
ERROR: No files to upload
ERROR: Job failed: exit status 2