Avoid triggering SYNC ge signals.

Fixes #5806, bcause it avoids rescheduling at the signal, which it should
not do.  Possibly this is incorrect for all GE signals, but we don't need
to trigger any behavior on a sync anyway.
Don't trigger pause GE signals either, comments.

This better explains what each signal does.
Handle GE pause signals per tests.

They really should pause, but we were resetting them incorrectly.
And most importantly, sceGeContinue() inside the signal handler absolutely
must work.  Games use this a lot.
Update GE lists when switching.

This uses a mutex, so it should be safe to do any time.  Really helps
debugging hung lists.
Don't mark a list complete too early.

This would matter probably mostly if we implemented CONTINUE properly.
Oops, downgrade from ERROR to DEBUG, and -report.
Merge pull request #5841 from unknownbrackets/ge-signals

Improve sync and pause GE signal handling