pkg/50826: pkgsrc USE_BSD_MAKEFILE doesn't seem to honor /etc/mk.conf

[paul%whooppee.com@localhost]

>Number:         50826
>Category:       pkg
>Synopsis:       pkgsrc USE_BSD_MAKEFILE doesn't seem to honor /etc/mk.conf
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Feb 18 07:30:00 +0000 2016
>Originator:     Paul Goyette
>Release:        NetBSD 7.99.26
>Organization:
+------------------+--------------------------+------------------------+
| Paul Goyette     | PGP Key fingerprint:     | E-mail addresses:      |
| (Retired)        | FA29 0E3B 35AF E8AE 6651 | paul at whooppee.com   |
| Kernel Developer | 0786 F758 55DE 53BA 7731 | pgoyette at netbsd.org |
+------------------+--------------------------+------------------------+
>Environment:
	
	
System: NetBSD pokey.whooppee.com 7.99.26 NetBSD 7.99.26 (POKEY 2016-02-16 03:01:55) #0: Tue Feb 16 12:33:45 PHT 2016 paul%pokey.whooppee.com@localhost:/build/netbsd-local/obj/amd64/sys/arch/amd64/compile/POKEY amd64
Architecture: x86_64
Machine: amd64
>Description:
	Ever since MKCTF and MKDTRACE were made default on amd64, the
	/usr/share/mk/ system assumes that ctf tools are available,
	unless MKCTF is set to "no".  For normal user builds, it is
	sufficient to add MKCTF=no to /etc/mk.conf 

	However, this seems to have no effect when building a pkgsrc
	package that uses USE_BSD_MAKEFILE.  Of the more than 400
	packages that I regularly build, the only one I have that uses
	USE_BSD_MAKEFILE is devel/tradcpp.  Building this package on a
	system that does not have the CTF tools results in an error
	similar to

	--- files.o ---
	ctfconvert -g -L VERSION files.o
	ctfconvert: not found
	*** [files.o] Error code 127

	This same error occurs whether or not MKCTF=no is set in
	/etc/mk.conf

	It _is_ possible to work around this by defining MKCTF=no in
	the environment prior to invoking make.
	
>How-To-Repeat:
	1. Build, install, and boot a -current system that does NOT
	   include MKDTRACE and MKCTF (alternatively, delete the ctf*
	   tools from an otherwise GENERIC system).
	2. Get pkgsrc
	3. Try to build the devel/tradcpp package - observe error
	4. Add MKCTF=np in /etc/mk.conf and try again - observe same error
	
>Fix:
	Unknown.  I'm guessing that, for pkgsrc, CTFCONVERT is being set
	early, prior to reading /etc/mk.conf, so there's probably some
	sort of sequencing issue or race condition.
	

>Unformatted: