Thread-safe runtime system

[Martin Sjölund]

This is a collection of non-threadsafe parts that we probably should resolve for bootstrapping if we want to run parallel omc:

• Message system (buffers)
• Jump buffers (setjmp; global, stack overflow, simulation stuff (less important))
• Java runtime (does anyone care?)
• Compiler/runtime: Need to consider error-buffers in parallel. Probably each thread wants its own error-stack to manipulate
• More?

[Martin Sjölund]

Thread-local storage possible to mimic globals

[Martin Sjölund]

pthread_rwlock_t to lock most global variables (we write to them very rarely, but we should lock them anyway).

[Martin Sjölund]

An fast and dirty solution for external C functions would be to add an annotation __OpenModelica_Mutex=true or __OpenModelica_Mutex="Name_of_Mutex" to avoid several functions from using the same resource. It does not solve the problem of shared global roots or the error buffer (which some threads want to roll back).

[Martin Sjölund]

The threadData is now used for most of these things, making many external functions possible to use in parallel.