inlining default

[Joe Buck]

> It seems that Neil's 2001-11-15 changes to option parsing had a side effect
> of turning on tree inlining at -O0 for C and C++ unless suppressed with
> -fno-inline, because we now set flag_tree_inline from flag_no_inline before
> setting flag_no_inline from optimize.  Is this what we want?

Probably not, because I'll bet that most people who say -O0 or who give
no -O switch at all are turning on -g, and inlining can make debugging
harder.