Configure option --with-smp-linux breaks loadable-module support

[serguei-patchkovskii]

Using configure --with-smp-linux produces an executable which will hang if loadable modules are used, and a program is loaded from the command line (i.e. combination of options dx -mdf ... -program ...). The workaround is to start OpenDX with the top-level picker menu (dx -mdf ...), then load the desired program with "Run Visual Programs ..."). Alternatively, do not use --with-smp-linux

The problem appears to be limited to the loadable-module initialization code: once the startup is successful, visual programs and loadable modules function normally.

[serguei-patchkovskii]

The issue appears fixed in the v4.4.5-sourceforge branch, which completely changes threading model on Linux (from multi-process to multi-threaded). Folding the fixes from the sourceforge branch will require some significant work though ...

[serguei-patchkovskii]

A test merge of the v4.4.5-sourceforge does not eliminate the problem (although apparently it allows OpenDX to start sometimes, suggesting a race condition during initialization).