libdrm_intel failed to be enabled by default

Hi,

In meson.build, we have (line 87):

with_intel = get_option('intel') \
  .require(with_atomics, error_message : 'libdrm_intel requires atomics') \
  .require(dep_pciaccess.found(), error_message : 'libdrm_intel requires libpciaccess') \
  .disable_auto_if(not host_machine.system().startswith('x86')) \
  .allowed()
summary('Intel', with_intel)

but it fails to built the libdrm_intel by default
It needs to be explicitly enabled (-Dintel=enabled) even with libpciaccess installed and detected on the system (x86_64)

Is that a normal behaviour ?
I also noticed, for whatever reason, libdrm_intel builds fine on Archlinux, without the option -Dintel=enabled

Also, I found a workaround, by replacing:

  .disable_auto_if(not host_machine.system().startswith('x86')) \  

with

  .disable_auto_if(not host_machine.cpu().startswith('x86')) \  

As I'm not a developer, all comments are welcome ;-)

OS: up-to-date Slackware-current
Arch: x86_64
libpciaccess: 0.17
libdrm: 2.4.117