ccc: Use CCC_NATIVE=1 by default.

 - So far this works fairly well for me for building applications
   using clang as a gcc substitute. If you are using ccc for a
   different purpose and this is a problem, speak up! Note you can
   also use CCC_NATIVE=0 to disable.

 - Also, turn CCC_ECHO off as default.

 - Also, pass through -Wl, to linker.

llvm-svn: 56904