Suppress Memcheck reports for http://build.chromium.org/p/tryserver.chromium/builders/mac_valgrind

(Mac OS 10.6 trybot):
 -- add a new suppression for bug 46186 (leak in HALCADClient::AddPropertyListener)
 -- expand suppression for bug 49250 (errors in remoting::CapturerMac::CaptureRects)
 -- suppress bug 68090 (conditional junp in BuildMacEncTable)
 -- suppress bug 68092 (uninitialized read in _CGSLockWindow)

BUG=46186,49250,68090,68092
TBR=timurrrr

Review URL: http://codereview.chromium.org/6057005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@70194 0039d316-1c4b-4281-b951-d872f2087c98