Despite the name, this package builds not only gcc, but also Newlib
and a simulator all in the same go. This procedure is documented at
[1] and has a few advantages:
 * We can avoid the bootstrap problem of needing gcc to build Newlib
   and needing Newlib to build gcc. Cycles like these normally need
   to be broken with build profiles [2].
 * We can also run the gcc test suite which isn't normally possible
   when building a cross compiler. The test suite relies on being
   able to run the target's binaries; we use a simulator from GDB,
   installed as sh-elf-run, to accomplish this.

[1] https://gcc.gnu.org/simtest-howto.html
[2] https://wiki.debian.org/DebianBootstrap
