[pph] Make pph.h _the_ interface header. (issue 5247044)

[dnovillo@google.com]

http://codereview.appspot.com/5247044/diff/1/gcc/cp/pph-streamer.h
File gcc/cp/pph-streamer.h (right):

http://codereview.appspot.com/5247044/diff/1/gcc/cp/pph-streamer.h#newcode165
gcc/cp/pph-streamer.h:165: struct pph_stream {
165 struct pph_stream {

You need the typedef.  Stage 1 is still built with C.

http://codereview.appspot.com/5247044/