Merge branch 'maint'

* maint:
  tests: fix a spurious failure with older flex versions

diff --cc t/lex-header.sh
index d50a1ef,ad2976e..f1283f6
--- 1/t/lex-header.sh
--- 2/t/lex-header.sh
+++ b/t/lex-header.sh
@@@ -18,8 -18,14 +18,14 @@@
  # bugs #8844 and #9933).
  
  required='cc flex'
 -. ./defs || exit 1
 +. test-init.sh
  
+ # Here, we need to use the use flex option '--header-file', but some
+ # older flex versions don't support is (see automake bug#11524 and
+ # bug#12836).  Skip this test if such an old flex version is detected.
+ $LEX --help | grep '.*--header-file' \
+   || skip_ "flex doesn't support the --header-file' option"
+ 
  cat >> configure.ac << 'END'
  AC_PROG_CC
  AC_PROG_LEX