Merge branch 'maint' into branch-1.11

Merge branch 'maint' into branch-1.11

* maint:
  tests: fix spurious failures with "chatty" make implementations
  tests: fix spurious failure on fast machines
  tests: avoid spurious failure of 'uninstall-fail.test' on Solaris
  tests: avoid spurious failure of 'uninstall-fail.test' on Cygwin
  tests: avoid spurious failure in 'parallel-tests3.test'
  tests: fix spurious failure with FreeBSD make and Yacc in VPATH
  tests: fix spurious failure with autoconf 2.62
  docs: avoid using colon character inside arguments of @pxref
  parallel-tests: warn on conditional TEST_EXTENSIONS definition
  parallel-tests: don't allow @substitutions@ in TEST_EXTENSIONS
  tests: fix spurious failure in 'insthook.test'
  maintcheck: fix spurious failure
  regenerate Makefile.in