Headers for the newlib toolchain
================================

The headers in the NaCl newlib toolchain come from several different
sources:

* headers in the newlib tree
* headers in src/untrusted/service_runtime/include/ some of which define the
  NaCl ABI and are shared with trusted code.
* headers in src/include/nacl/, which are NaCl-specific and can also be used
  with glibc.
* headers in src/untrusted/nacl/include/, which are newlib-specific and extend
  the C library.  These aren't part of NaCl's stable ABI.