[PATCH v2 0/2] Allow detection of missing XInitThreads calls.

[Rami Ylimäki]

Previous version of the change initialized threads by default. Such
feature allows unsafe X clients to work when they shouldn't.

This version makes multithreaded X clients abort with an error message
if they enter a critical section concurrently before XInitThreads is
called. After the first XInitThreads call from the client, situation
is normalized.

The difference is that with reconfigured Xlib, unsafe X client abort
in a predictable place instead of crashing in random locations.