engine: add missing libm dependency

floor() is now used at rfc822-message-data.vala:213 via GLib.Math.floor
5 jobs for libm-dep in 65 minutes and 39 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #269700
fedora

00:03:40

passed #269701
ubuntu

00:42:42

 
  Test
passed #269702
flatpak

00:21:46

 
  Deploy
passed #269703
review

00:00:38

failed #269704
allowed to fail manual
stop_review

00:00:32

 
Name Stage Failure
failed
stop_review Deploy
 * [new tag]         geary-0.8.0             -> geary-0.8.0
* [new tag] geary-0.8.1 -> geary-0.8.1
* [new tag] geary-0.8.2 -> geary-0.8.2
* [new tag] geary-0.8.3 -> geary-0.8.3
* [new tag] geary-0.9.0 -> geary-0.9.0
* [new tag] geary-0.9.1 -> geary-0.9.1
Checking out 6acddfd0 as libm-dep...
fatal: reference is not a tree: 6acddfd02c00edcc8a3a738cfc193131dd170a15
ERROR: Job failed: exit code 1