platform-openh264: Don't provide for arm, ppc

The binary from cisco is either x86_64 or i*86, so no need to build for
arm or ppc.
10 jobs for coldtom/publish-openh264 in 103 minutes and 28 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Flatpak
passed #295545446
aarch64
app_aarch64

01:40:57

passed #295545447
armhf
app_arm

00:40:11

passed #295545445
cache_i686 x86_64
app_i686

01:26:25

passed #295545448
ppc64le allowed to fail
app_powerpc64le

01:23:37

passed #295545444
cache_x86_64 x86_64
app_x86_64

01:24:42

 
  Vm
manual #295545451
aarch64 allowed to fail manual
minimal_systemd_vm_aarch64
passed #295545452
armhf
minimal_systemd_vm_arm

00:02:30

passed #295545450
cache_i686 x86_64
minimal_systemd_vm_i686

00:01:12

manual #295545453
ppc64le allowed to fail manual
minimal_systemd_vm_powerpc64le
passed #295545449
cache_x86_64 x86_64
minimal_systemd_vm_x86_64

00:01:19