Merge remote-tracking branch 'origin/maint'

* origin/maint:
  maint: post-release administrivia
  version 3.0.4
  gnulib: update
  build: re-enable compiler warnings, and fix them
  tests: c++: fix a C++03 conformance issue
  tests: fix a title
  c++: reserve 200 slots in the parser's stack
  tests: be more robust to unrecognized synclines, and try to recognize xlc
  tests: fix C++ conformance
  build: fix some warnings
  build: avoid infinite recursions on include_next