self-compile time <5 minutes

[Stephen Weeks]

Yeah!  We're back under 5 minutes again for a self-compile (generating 
C).   Here's the gc-summary.

% time ../bin/mlton -C -no-polyvariance -inline 30 mlton.sml
max semispace size(bytes): 183,500,800
GC time(ms): 109,630 (36.9%)
maxPause(ms): 5,290
number of GCs: 50
bytes allocated: 6,202,034,456
bytes copied: 1,957,619,404
max bytes live: 93,311,336
288.07user 10.11system 4:59.26elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (2742major+415626minor)pagefaults 0swaps