Merge remote-tracking branch 'origin/maint'

Merge remote-tracking branch 'origin/maint'

* origin/maint:
  tests: headers.at: strengthen.
  glr.cc: do not override C++ definitions by C macros.
  YYLLOC_DEFAULT: factor, and don't export it in headers.
  api.prefix: do not use #define to handle YYSTYPE_IS_TRIVIAL etc.
  tests: portability fixes.
  c++: fewer #includes in the headers.
  glr.cc: formatting changes.
  tests: more logs.
  api.prefix: also rename YYDEBUG.

Conflicts:
	data/c.m4
	data/glr.c
	data/glr.cc
	data/lalr1.cc
	data/yacc.c