[PATCH v3 0/3] Allow detection of missing XInitThreads calls.

[Rami Ylimäki]

v1:
The change initialized threads by default. Such feature allows unsafe
X clients to work when they shouldn't.

v2:
Fixes problems in v1 and 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 clients abort
in a predictable place instead of crashing in random locations.

v3:
Fixes dependencies between libX11 and libX11-xcb during
build process and also in the built libraries. These libraries have
been now made more independent.