Trim the list of signals used by debug_util::DisableOSCrashDumps() on Mac

Trim the list of signals used by debug_util::DisableOSCrashDumps() on Mac.

The list was too long and was catching signals corresponding to Mach
exceptions that Apple Crash Reporter never attempts to catch, and signals
that don't even map to Mach exceptions.  The default signal handlers are fine
in these cases.

BUG=24568
TEST=Crash reporting still disabled when appropriate
     (see chrome/app/chrome_dll_main.cc and the comment before
     DisableOSCrashDumps in ChromeMain)
     Specifically, with stats reporting disabled, about:crash should result in
     a sad tab but no silent crash report generated in
     ~/Library/Logs/CrashReporter

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=28701

[TVL, 2009-10-12 11:27:48]

lgtm

(fyi - the other list i think came from testshell at one time, and that list
came from dump render tree)

[jeremy, 2009-10-12 20:48:47]

LGTM