Apparently the hack to get release and debug viewer builds into separate build configs means checking  in build.sh is useless. Fixed the conditional around uploading the symbolfile to check  instead, which seems to be the correct pattern.

WOLF-363: (partial) correct ordering of cleaning build dir vs running
          'autobuild install'

Fix for CHOP-619.  Found a general solution to our vs2010 precompiled headers problems and eliminated all our special cases for handling them.

viewer_manifest.py will now package a summary.json file, if present; but
previously build.sh didn't create that file until after the viewer build.

Patch taken from here: https://paste.lindenlab.com/show/6902/

Setting TMP env var to be used during builds. Possible collision when using VS2010 with system-wide TMP directory.

Also temporarily disabling Debug and Release builds to get a faster loop cyle on TC.

Reviewed by CG.

Have build.sh print out info usable by open source devs. Have it check for a README and use that if needed.