target.h and alloc-pool.h are not required by any of the streamer header
files to compile, so I flattened those 2 includes from lto-streamer.h.
plugin-api.h, gcov-io.h and diagnostic.h are all required to parse
lto-streamer.h, so I left those in the file.
I then ran the include reducer on all of the files which were affected
by by the flattening (there were 38). I had it only consider the
affected files : target.h, alloc-pool.h and lto-streamer.h.
Only 22 of the 38 files now show any change, and in many of those cases
it was removing lto-streamer.h itself that was the end result :-) So
its a much cleaner patch now :-)
Bootstraps on x86_64-unknown-linux-gnu with no new regressions.
OK for trunk?