gltrace: Forward unhandled signals/exceptions to a next handler
gltrace: Forward unhandled signals/exceptions to a next handler

Some applications have custom handler for signals/exceptions,
which is necessary for their working. Therefor we shall forward
all unhandled signals/exceptions down the road.

Also apitrace itself has custom logic for handling signals,
which failed to execute due to lack of signal forwarding in
GLMemoryShadow.

Fixes a crash when tracing rpcs3.

Fixes: 18ce32f949409d051c88aea62209818aec7d6aa5
Signed-off-by: Danylo Piliaiev <5f5cc2800158177d93bace49e53f670cfc7abed2@globallogic.com>

apitrace/apitrace,apitrace/apitrace,apitrace/apitrace,apitrace/apitrace