[PATCH] Fix AT_ARG_OPTION_ARG handling of options with hyphens.

The manual says that given e.g., AT_ARG_OPTION_ARG([my-option],
[  --my-option=ARG]), the user can pass either --my-option=val
or --my-option val to the testsuite with equivalent results.

However, if the option name contains a hyphen, only the first
form actually works because the argument parser combines the
two arguments into --my_option=val which it immediately confuses
for an invalid variable assignment, for example:

  % ./testsuite --my-option val
  testsuite: error: invalid variable name: `--my_option'

* lib/autotest/general.m4 (_AT_ARG_OPTION): Set at_prev to untransformed
option name to fix argument parsing for options containing hyphens.
* tests/autotest.at (AT_ARG_OPTION_ARG): Ensure the two-argument form
for options containing hyphens is covered by the test suite.
---
 lib/autotest/general.m4 | 2 +-
 tests/autotest.at       | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/autotest/general.m4 b/lib/autotest/general.m4
index 5d89d0c06937..f58f111a7626 100644
--- a/lib/autotest/general.m4
+++ b/lib/autotest/general.m4
@@ -1712,7 +1712,7 @@ m4_divert_text([PARSE_ARGS],
 [dnl Parse the options and args when necessary.
 m4_ifvaln([$3],
 [    AT_case )
-	at_prev=--AT_first_option_tr
+	at_prev=--AT_first_option
 	;;
     AT_case_arg )
 	at_arg_[]AT_first_option_tr=$at_optarg
diff --git a/tests/autotest.at b/tests/autotest.at
index 7734277f021f..405a05fa11c6 100644
--- a/tests/autotest.at
+++ b/tests/autotest.at
@@ -1358,7 +1358,8 @@ for args in \
   '1 --fro=bar FROB=bar FROB_ARG=bar' \
   '1 --frob=bar FROB=bar FROB_ARG=bar' \
   '2 expected=' \
-  '2 --opt-with-hyphen=baz expected=baz'
+  '2 --opt-with-hyphen=baz expected=baz' \
+  '2 --opt-with-hyphen baz expected=baz'
 do
   AT_CHECK([$CONFIG_SHELL ./micro-suite -x $args], [], [ignore])
 done
-- 
2.24.1