Optimization: toolset variables setting

From: Vladimir Prus (ghost_at_[hidden])
Date: 2004-12-22 03:09:39

It turns out that even more work of setting target variables can be done one 
per property-set, as opposed to once per target.

Compatibility: only Boost.Build update required

Performance: a couple of seconds went to running time graveyard. No bad for 10 
mins of hacking.

Femtown (reference Boost.Build)
Real: min 21:510, max 22:110, avg 21:796
User: min 19:780, max 20:190, avg 20:3

Femtown (CVS Boost.Build)
Real: min 18:520, max 20:130, avg 19:93
User: min 17:430, max 17:940, avg 17:673

TBLib (reference Boost.Build)
Real: min 11:770, max 12:50, avg 11:920
User: min 10:920, max 11:80, avg 11:3

TBLib (CVS Boost.Build)
Real: min 10:340, max 10:540, avg 10:420
User: min 9:980, max 10:160, avg 10:76

Note: the 'reference time' is a bit larger than previous 'CVS results' due to 
higher load on the test system.