Dyson

GCJ was first built for GCC 4.7.0, then it was always FTBFS due to crashing in gjdoc and other utilities,
but GCJ 4.7.0 was not fully usable: it hanged under some conditions (#186), that made OpenJDK 7 a bit harder.

Now all isssues are resolved:

• boehm-gc needs some symbols
• multithreaded compilation in ecj1 (gcj frontend) was disabled.