toolchain/47273: toolchain doesn't respect TMPDIR and uses stupid default

[Taylor R Campbell <campbell+netbsd%mumble.net@localhost>]

>Number:         47273
>Category:       toolchain
>Synopsis:       toolchain doesn't respect TMPDIR and uses stupid default
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Dec 02 00:25:00 +0000 2012
>Originator:     Taylor R Campbell <campbell+netbsd%mumble.net@localhost>
>Release:        NetBSD-current
>Organization:
>Environment:
>Description:

        `env TMPDIR=/tmp/lose ./build.sh ...' doesn't make GCC (and
        maybe other tools too) use /tmp/lose for its temporary
        directories; instead it stupidly uses /var/tmp, which is for
        temporary storage that is supposed to persist across a reboot.

>How-To-Repeat:

        Mount a synchronous ffs on /var so that it is reliable but
        slow.  Mount tmpfs on /tmp so that it is transient but fast.
        Run build.sh and observe that the C compiler dumps the
        ccXYZ123PQR.s files in /var/tmp instead of /tmp by default.
        Run `env TMPDIR=/tmp/lose ./build.sh ...' and observe that the
        C compiler *still* dumps crap in /var/tmp.  Throw up your hands
        in frustration and break /var/tmp by mounting a tmpfs there so
        that builds will finish in reasonable amounts of time.

>Fix:

        Yes, please!