Update tests/presubmit.sh to accept Fuchsia bugs as fxb/#

Allow the Bug prefix fxb/ to be used to Fuchsia bug numbers
in commit messages. These should be redirected to
https://fxbug.dev/<number>

Bug: None
Change-Id: Ibdba2b22b15cc6851dccc60e64bea034b8be668a
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/44129
Presubmit-Ready: David Turner <digit@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Tested-by: David Turner <digit@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
diff --git a/tests/presubmit.sh b/tests/presubmit.sh
index 810309b..3b32cd7 100755
--- a/tests/presubmit.sh
+++ b/tests/presubmit.sh
@@ -40,13 +40,14 @@
 
 # Validate commit message
 function run_bug_in_commit_msg() {
-  git log -1 --pretty=%B | grep -E '^(Bug|Issue|Fixes):(\s?)(((b\/)|(\w+:))([0-9]+)|[^0-9]+)$|(^Regres:)|(^PiperOrigin-RevId:)'
+  git log -1 --pretty=%B | grep -E '^(Bug|Issue|Fixes):(\s?)((((b|fxb)\/)|(\w+:))([0-9]+)|[^0-9]+)$|(^Regres:)|(^PiperOrigin-RevId:)'
 
   if [ $? -ne 0 ]
   then
     echo "${red}Git commit message must have a Bug: line"
     echo "followed by a bug ID in the form b/# for Buganizer bugs or"
-    echo "project:# for Monorail bugs (e.g. 'Bug: chromium:123')."
+    echo "project:# for Monorail bugs (e.g. 'Bug: chromium:123') or"
+    echo "fxb/# For Fuchsia bugs (e.g. 'Bug: fxb/123')."
     echo "Omit any digits when no ID is required (e.g. 'Bug: fix build').${normal}"
     return 1
   fi