build: fix default drivers list without Python

build: fix default drivers list without Python

If no enable_drivers option is passed, the default is to build
the drivers list by calling list-dir-globs.py.

But if no Python interpreter is installed, no error is reported
and all drivers end up being disabled.

Example on a minimal FreeBSD VM:

  dpdk@freebsd:~/dpdk $ meson setup build
  ...
  drivers:
	  common/cpt:	not in enabled drivers build config
	  common/dpaax:	not in enabled drivers build config
	  common/iavf:	not in enabled drivers build config
	  common/mvep:	not in enabled drivers build config
	  common/octeontx:	not in enabled drivers build config
	  common/octeontx2:	not in enabled drivers build config
	  bus/dpaa:	not in enabled drivers build config
	  bus/fslmc:	not in enabled drivers build config
  ...

  dpdk@freebsd:~/dpdk $ cd drivers/
  dpdk@freebsd:~/dpdk/drivers $ ~/dpdk/buildtools/list-dir-globs.py */*
  env: python3: No such file or directory

Rely on meson internal interpreter.
Check return code when calling this script.

Fixes: ab9407c3addd ("build: allow using wildcards to disable drivers")
Fixes: 2e33309ebe03 ("config: enable/disable drivers in Arm builds")
Cc: stable@dpdk.org
Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>