Add an utility to cancel a build

Usage:

$ cancel_build 20231231211004.pterjan.duvel.1487312
*: [cancel_build] check uploads tree
I: [cancel_build] check dir: /var/lib/schedbot/uploads/done
I: [cancel_build] check dir: /var/lib/schedbot/uploads/todo
I: [cancel_build] Failing 20231231211004.pterjan.duvel.1487312 and cleaning up done architectures
I: [cancel_build] Killing process 1146007 on rabbit2 (building for arch "i586")
I: [cancel_build] Killing process 2204767 on ecosse0 (building for arch "x86_64")
I: [cancel_build] Killing process 3092253 on ociaa1-a (building for arch "aarch64")
I: [cancel_build] Killing process 3092165 on ociaa1-b (building for arch "armv7hl")

1 files changed, 1 insertions, 1 deletions

diff --git a/emi b/emi
index e697e4a..1cdad5d 100755
--- a/emi
+++ b/emi
@@ -92,7 +92,7 @@ config_init(\%config_usage, $config, \%run);
 
 $run{pidfile_home} = $config->{tmp};
 $run{pidfile} = "upload";
-my $pidfile = check_pid(\%run);
+my $pidfile = check_pid(\%run, 1);
 
 my $todo = "$config->{queue}/todo";
 my $done = "$config->{queue}/done";