pkg/50658: bootstrap using 64bit ABI broken on Solaris 11.2

[joern.clausen%uni-bielefeld.de@localhost]

>Number:         50658
>Category:       pkg
>Synopsis:       bootstrap using 64bit ABI broken on Solaris 11.2
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jan 15 09:45:00 +0000 2016
>Originator:     Joern Clausen
>Release:        
>Organization:
University of Bielefeld
>Environment:
SunOS pkgsrc-sol11i86 5.11 11.2 i86pc i386 i86pc

>Description:
Bootstrapping a recently synced pkgsrc tree on Solaris 11.2/i86 with 

./bootstrap --abi 64 ...

results in an error while installing bootstrap-mk-files:

===> Install binary package of bootstrap-mk-files-20150908
pkg_add: Warning: package `bootstrap-mk-files-20150908' was built for a platform:
pkg_add: SunOS/x86_64 5.11 (pkg) vs. SunOS/i386 5.11 (this host)
pkg_add: 1 package addition failed

The binaries generated so far are indeed 32 bit:

$ file work/sbin/pkg_add 
work/sbin/pkg_add:      ELF 32-bit LSB executable 80386 Version 1, dynamically linked, not stripped

I have successfully bootstrapped older pkgsrc releases on the same machine using the 64 bit ABI option and the same compiler.
>How-To-Repeat:

>Fix: