Allow CDSA/CSSM to be used on worker threads in debug builds

Allow CDSA/CSSM to be used on worker threads in debug builds by making both the CSSM init singleton and the Mac Security Services lock singleton leaky.

This primarily affects the use of <keygen> in a debug build, as the RSA private key is generated on a worker thread and needs to hold the Mac Security Services lock.

BUG=none
TEST=none

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=72580

[Ryan Sleevi, 2011-01-23 22:42:40]

wtc: Just a minor change, matching the leakiness of NSS, so that <keygen> can be
used in the browser in Debug builds.

[wtc, 2011-01-25 00:55:17]

LGTM.

Nit: in the CL's description, change
    CSSM lock Singleton
to
    Mac Security Services lock Singleton