That is, move the pc/ln table and the symbol table
into the read-only data segment.  This eliminates
the need for a special load command to map the
symbol table into memory, which makes the
information available on systems that couldn't handle
the magic load to 0x99000000, like NaCl and ARM QEMU
and Linux without config_highmem=y.  It also
eliminates an #ifdef and some clumsy code to
find the symbol table on Windows.

The bad news is that the binary appears to be bigger
than it used to be.  This is not actually the case, though:
the same amount of data is being mapped into memory
as before, and the tables are still read-only, so they're
still shared across multiple instances of the binary as
they were before.  The difference is just that the tables
aren't squirreled away in some section that "size" doesn't
know to look at.

This is a checkpoint.
It probably breaks Windows and breaks NaCl more
than it used to be broken, but those will be fixed.
The logic involving -s needs to be revisited too.

Fixes #871.

R=ken2
CC=golang-dev
https://golang.org/cl/2587041