gnulib-tool: Add support for Automake 1.16.4

[Bruno Haible]

It was reported in
<https://lists.gnu.org/archive/html/bug-libunistring/2021-08/msg00000.html>
that the test-driver.diff does not work against the 'test-driver' file
from Automake 1.16.4 (that was released on 2021-07-26):

  patching file build-aux/test-driver
  Hunk #1 FAILED at 106.
  1 out of 1 hunk FAILED -- saving rejects to file build-aux/test-driver.rej

With this patch, I'm adding support for Automake 1.16.4.


2021-08-07  Bruno Haible  <bruno@clisp.org>

        gnulib-tool: Add support for Automake 1.16.4.
        Reported by <shoober420@gmail.com> in
        
<https://lists.gnu.org/archive/html/bug-libunistring/2021-08/msg00000.html>.
        * build-aux/test-driver-1.16.3.diff: Renamed from
        build-aux/test-driver.diff.
        * build-aux/test-driver.diff: Update to match Automake 1.16.4.
        * gnulib-tool (func_create_testdir, func_create_megatestdir): Try both
        .diff files.

diff --git a/build-aux/test-driver.diff b/build-aux/test-driver-1.16.3.diff
similarity index 100%
copy from build-aux/test-driver.diff
copy to build-aux/test-driver-1.16.3.diff
diff --git a/build-aux/test-driver.diff b/build-aux/test-driver.diff
index b81e5a1..53d7ef7 100644
--- a/build-aux/test-driver.diff
+++ b/build-aux/test-driver.diff
@@ -1,14 +1,14 @@
---- test-driver.bak    2019-01-23 03:22:06.672283432 +0100
-+++ test-driver        2019-01-23 04:23:21.201060757 +0100
-@@ -106,7 +106,10 @@
- trap "st=143; $do_exit" 15
-
- # Test script is run here.
--"$@" >$log_file 2>&1
+--- test-driver.bak    2021-08-04 11:12:04.399976745 +0200
++++ test-driver        2021-08-04 11:17:17.646343985 +0200
+@@ -109,7 +109,10 @@
+ # to ameliorate tests themselves also writing to the log file. Our tests
+ # don't, but others can (automake bug#35762).
+ : >"$log_file"
+-"$@" >>"$log_file" 2>&1
 +case "$1" in
-+  *.sh) sh "$@" >$log_file 2>&1 ;;
-+  *)    "$@" >$log_file 2>&1 ;;
++  *.sh) sh "$@" >>"$log_file" 2>&1 ;;
++  *)    "$@" >>"$log_file" 2>&1 ;;
 +esac
  estatus=$?
-
+ 
  if test $enable_hard_errors = no && test $estatus -eq 99; then
diff --git a/gnulib-tool b/gnulib-tool
index 63a875d..9c4a6c1 100755
--- a/gnulib-tool
+++ b/gnulib-tool
@@ -6767,7 +6767,9 @@ func_create_testdir ()
   fi
   (cd "$testdir"
    if test -f build-aux/test-driver; then
-     patch build-aux/test-driver < "$gnulib_dir"/build-aux/test-driver.diff || 
func_exit 1
+     patch build-aux/test-driver < "$gnulib_dir"/build-aux/test-driver.diff \
+       || patch build-aux/test-driver < 
"$gnulib_dir"/build-aux/test-driver-1.16.3.diff \
+       || func_exit 1
    fi
   ) || func_exit 1
 }
@@ -6871,7 +6873,9 @@ func_create_megatestdir ()
    func_execute_command ${AUTOMAKE} --add-missing --copy || func_exit 1
    rm -rf autom4te.cache
    if test -f build-aux/test-driver; then
-     patch build-aux/test-driver < "$gnulib_dir"/build-aux/test-driver.diff || 
func_exit 1
+     patch build-aux/test-driver < "$gnulib_dir"/build-aux/test-driver.diff \
+       || patch build-aux/test-driver < 
"$gnulib_dir"/build-aux/test-driver-1.16.3.diff \
+       || func_exit 1
    fi
   ) || func_exit 1
 }