Tolerate missing debug info in the shared_ptr pretty printer.

Certain fields of shared ptr have virtual functions and therefore
have their debug info homed in libc++. But if libc++ wasn't built
with debug info, the pretty printer would fail.

This patch makes the pretty printer tolerate such conditions and
updates the test harness.

This patch significantly reworks a previous attempt.

This addresses

Differential Revision:

GitOrigin-RevId: 55b7061116b5f0f839bd4240c3c6fba63918b816
3 files changed