Merge remote-tracking branch 'origin/maint'

* origin/maint:
  tests: do not output m4 set up.
  tests: use the generic yyerror function.
  tests: use assert instead of plain abort.
  tests: improve the generic yylex implementation.
  tests: generalize the compilation macros.
  tests: fix confusion between api.prefix and name-prefix.
  maint: gitignores.
  yacc: work around the ylwrap limitation.

Conflicts:
	NEWS
	tests/local.at

build-aux/snippet/.gitignore

@@ -0,0 +1,4 @@
+/_Noreturn.h
+/arg-nonnull.h
+/c++defs.h
+/warn-on-use.h