Fix a few documents fixmes

A few patches that (hopefully) don't change the behavior of git except to rectify a memory error. Also, this should ever so slightly help with the parallelism of git (a GSoC proposal). All of these were found with commented FIXME and git grep.

Jared Hance (3):
Use startup_info->prefix rather than prefix. Fix memory leak in apply_patch in apply.c. Add threaded versions of functions in symlinks.c.

 builtin/apply.c |   30 +++++++++++++++++++++++++++---
 cache.h         |    4 +++-
 git.c           |    2 +-
 symlinks.c      |   28 ++++++++++++++++++++++++++--
 trace.c         |   10 +++++-----
 5 files changed, 62 insertions(+), 12 deletions(-)

Changelog since last series submission:
    - Whitespace fixes that I should have checked for before
    - Typo fix
    - Completely redo my fix to the memory leak to address issues pointed
      out by Junio.

Note: I'm not quite sure if I actually agree with the first change. It makes
sense right now if git.c is the only caller, but in the future, it might become
less flexible. It might be wise to actually make startup_info static to git.c
for protection in the future. They should be relatively independent, though,
so the 2nd and 3rd which are probably less controversal can easily be applied.

1.7.3.4