pkg/42473: Tru64: devel/libffi occasionally fails to build with MAKE_JOBS >1

[rumi%rtfm.hu@localhost]

>Number:         42473
>Category:       pkg
>Synopsis:       Tru64: devel/libffi occasionally fails to build with MAKE_JOBS 
>>1
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Dec 18 22:35:00 +0000 2009
>Originator:     Szabolcs Rumi
>Release:        Tru64 5.1B-5
>Organization:
>Environment:
# sizer -v
HP Tru64 UNIX V5.1B (Rev. 2650); Thu Dec 17 18:47:21 CET 2009
# cc -V
Compaq C V6.5-303 (dtk) on HP Tru64 UNIX V5.1B (Rev. 2650)
Compiler Driver V6.5-302 (dtk) cc Driver
# cxx -V
Compaq C++ V7.1-006 for HP Tru64 UNIX V5.1B (Rev. 2650)
Compiler Driver V7.1-006 (cxx) cxx Driver
# cat /usr/pkgsrc/CVS/Tag
Tpkgsrc-2009Q3

>Description:
--- libffi_convenience.la ---
ar: Error: src/alpha/.libs/osf.o cannot open
*** [libffi_convenience.la] Error code 1
--- libffi.la ---
/usr/bin/ld:
Can't open: src/alpha/.libs/osf.o (No such file or directory)
*** [libffi.la] Error code 1
2 errors

bmake: stopped in /usr/pkgsrc/devel/libffi/work/libffi-3.0.8
*** [all-recursive] Error code 1
1 error

I've been trying this with MAKE_JOBS=6 (on a 4 CPU machine).
Compilation sometimes breaks like above, while at other times it succeeds.
Apparently with MAKE_JOBS=1 it always succeeds.

>How-To-Repeat:

>Fix:
MAKE_JOBS_SAFE=no