move exec_make_note_section earlier

This patch moves exec_make_note_section a bit earlier in exec.c.  This
lets us remove an otherwise unnecessary forward declaration and it
also makes the file a bit more in line with other code, as now
_initialize_exec is the final function in the file.

Tested by rebuilding.
I'm committing this as obvious.

2014-07-18  Tom Tromey  <tromey@redhat.com>

	* exec.c (exec_make_note_section): Move earlier.