Clean up symbol table access functions and make it

Clean up symbol table access functions and make it
possible to inline them.  The symbol table is heavily
used in the stacktrace code and the faster access
functions should help out.

base/loader/symtab.cc:
    Put these in the header file since they are simple and can
    be inlined.
base/loader/symtab.hh:
    Move the various findFoo functions to the header file so they
    can be inlined.  Add findNearestAddr functions that don't
    return the symbol.  This is so you can figure out what
    function you're in based on the symbol table, but not waste
    time copying out the symbol name if you don't need it.

--HG--
extra : convert_revision : 00cac40a79b0641a70c5ec7d9838fa0ec505c6a1