[ros-dev] patch for test/review

[Hartmut Birr]

Hi,

I've changed rbuild a little bit, that it can run on msys (on windows). 
The major changes are:
- The separator (slash or back slash), exepostfix and exeprefix are 
initialized from environment variables.
- The separators in the path for the system command are always converted 
for the host system.
- Our own build utilities must convert paths itself (bin2res).
It exist some problems with absolute paths on msys, because msys uses 
'/c/foo/bar' and windows 'c:\foo\bar' or 'c:/foo/bar'.

I've tested the patch on msys and on windows. I cannot test the patch on 
linux.

Currently, msys is the only way to use all cpus or cores for the build 
process on windows.

- Hartmut