Failure message when inconsistent X11_TYPE

[Frederic Fauberteau <triaxx%NetBSD.org@localhost>]

I submitted PR pkg/56299 because I encountered a failure with a misconfigured sandbox (I set --without-x instead of --without-xsrc). But the problem is not really related to mksandbox. Actually, X11_TYPE is set by default to native even if the xbase set is not installed. As discussed with David Holland, it doesn't seem reasonable to conditionally set X11_TYPE to modular in case of xbase is not installed. But maybe we could fail with an explicit message in this particular case.

Is there any objection to such a commit?

--- mk/platform/NetBSD.mk       25 Apr 2021 07:51:25 -0000      1.65
 +++ mk/platform/NetBSD.mk       8 Jul 2021 20:50:14 -0000
 @@ -45,6 +45,9 @@
  # to modular.
  .if empty(MACHINE_PLATFORM:MNetBSD-[0-5].*)
  X11_TYPE?=             native
 +.  if !empty(X11_TYPE:Mnative) && !exists(/etc/mtree/set.xbase)
 +PKG_FAIL_REASON+=      "Native X11 distribution cannot be used if xbase set has not been installed. You should set X11_TYPE=modular or install xbase set."
 +.  endif
  .endif
  
  _OPSYS_EMULDIR.aout=           /emul/aout