Merge r1432:1437 from /branches/newlib into /trunk :
- under bare-metal, the user is responsible for providing a gdbserver stub (r1433)
- install a CT_TARGET-cc -> CT_TARGET-gcc symlink for the core gcc (r1434)
- allow broader dependency in generated config files (r1435, r1436)
- prepare C library menuconfig for using a C library under bare-metal (r1437)