Okay, building OpenSolaris with the opensolaris.sh environment inside SWAN is different. I first tried it with:

% ws cleanroom
% nightly opensolaris.sh

And got garbage. I tried palying with some environment variables and didn't get anywhere. I then tried it with bldenv:

% exit
% cd cleanroom
% bldenv -d opensolaris.sh
% nightly opensolaris.sh

That went fast:

/opt/SUNWspro/bin/dmake
dmake: Sun Distributed Make 7.7 2005/10/13
number of concurrent jobs = 36

No 32-bit compiler found
*** Error code 1
The following command caused the error:
if /builds/th199096/cleanroom/usr/src/tools/proto/opt/onbld/bin/i386/cw -_cc -_versions >/dev/null 2>/dev/null; then \

Finally, I went back to the ws approach and with the following opensolaris.sh diffs:

[th199096@jhereg cleanroom]> diff opensolaris.sh usr/src/tools/env/opensolaris.sh 
45c45
< GATE=cleanroom;                       export GATE
---
> GATE=testws;                  export GATE
48c48
< CODEMGR_WS="/builds/th199096/$GATE";                  export CODEMGR_WS
---
> CODEMGR_WS="/export/$GATE";                   export CODEMGR_WS
91c91
< STAFFER=th199096;                             export STAFFER
---
> STAFFER=nobody;                               export STAFFER
157c157
< #BUILD_TOOLS=/opt;                            export BUILD_TOOLS
---
> BUILD_TOOLS=/opt;                             export BUILD_TOOLS
159,161c159,160
< #SPRO_ROOT=/opt/SUNWspro;                     export SPRO_ROOT
< #SPRO_VROOT=$SPRO_ROOT;                               export SPRO_VROOT
< #__SSNEXT="";                                 export __SSNEXT
---
> SPRO_ROOT=/opt/SUNWspro;                      export SPRO_ROOT
> SPRO_VROOT=$SPRO_ROOT;                                export SPRO_VROOT
186d184
< export CW_NO_SHADOW=1

That seems to have worked. Now I need to test a pNFS community setup and run cthon.