Make FMU Compile without configure script

[Martin Sjölund]

If we assume that the user of the FMU has nothing installed on his system and wants the most bare-bone FMU we could possibly compile, it should be possible to compile the FMU is a standard way:

<ModelExchange> and <Co-Simulation> XML tags have a <SourceFiles> tag with a list of <File> that we could use to specify all files necessary to compile the FMU (note: this requires OM finding out which these files are at OMC compile-time or reading some structure later).

It would be nice if the C-code also worked without setting gcc include directives like -I include/fmi2.

One problem is of course how to deal with external build projects like ModelicaExternalC.

We should still support the configure script though since it takes care of a lot of extras for us.

[Martin Sjölund]

We now have the autoconf/configure results cached for when we compile for the current platform. The other parts in the ticket are not considered though.