[0/10] RFC: remove obj_section field

[Tom Tromey]

This series removes general_symbol_info::obj_section.

The immediate benefit of doing this is that it shrinks all symbols by a
whole pointer.  This is a reasonably good memory savings.

This series also has the nice effect of regularizing section indices:
now the SYMBOL_SECTION is the same (modulo minor weirdness, see patch
#6) as the BFD section index.


This series also supports my long-term goal of "objfile splitting".  At
least patches 2, 3, and 4 go in this direction, by removing one
symbol->objfile backlink, and by introducing "bound minimal symbols".
I'll describe this more in those patches.


I've built and regtested this series on x86-64 Fedora 16, on PPC Fedora
18 (gcc110 in the compile farm), and on HP-UX.  I also built and
regtested it on x86-64 Fedora 16 using -gstabs+.

However, it could certainly use more testing and inspection.  The
individual patch messages will point out some of the questionable bits.

Joel, I will push a new branch for you to test, if you don't mind.  I'll
send email when it is ready.

Tom