libcpp built by host compiler?

[Aaron W. LaFramboise]

While investigating wrong-code PR gcc/18139
<http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18139>, I noticed that,
during a normal bootstrap, libcpp is built by the host compiler, but
never re-built by the bootstrapped compilers.  This results in the
libcpp portion of the final gcc executables being compiled by the host
compiler rather than by the bootstrapped compiler.

Isn't all of GCC supposed to be bootstrapped, including libcpp?

Aaron W. LaFramboise