Use task_info(..., TASK_DYLD_INFO, ...) on 10.6 and later

Use task_info(..., TASK_DYLD_INFO, ...) on 10.6 and later in preference to
looking up the _dyld_all_image_infos symbol in /usr/lib/dyld.

Landed

[mochalatte]

LGTM

http://breakpad.appspot.com/276001/diff/2001/4
File src/client/mac/handler/dynamic_images.cc (right):

http://breakpad.appspot.com/276001/diff/2001/4#newcode375
Line 375: #else
nit: i don't think this preprocessor optimization is necessary, it seem simpler
to just use the OS API all the time, especially since it's cached via the static
function variable in GetOSVersion

[Mark Mentovai]

http://breakpad.appspot.com/276001/diff/2001/4
File src/client/mac/handler/dynamic_images.cc (right):

http://breakpad.appspot.com/276001/diff/2001/4#newcode375
Line 375: #else
mochalatte wrote:
> nit: i don't think this preprocessor optimization is necessary, it seem
simpler
> to just use the OS API all the time, especially since it's cached via the
static
> function variable in GetOSVersion

I disagree. This will cause all of the static functions to disappear, and
GetDyldAllImageInfosPointer to have the impossible branch optimized out. It’s a
code size win for any products that don’t care about 10.5 or earlier. This is a
fairly standard way that I handle OS feature availability.