automake: add missing AC_MSG_RESULT calls to AM_SANITY_CHECK.

From https://bugs.gnu.org/76448 (automake-patches).

* m4/sanity.m4 (AM_SANITY_CHECK): Call AC_MSG_RESULT before erroring
out so that a complete line is printed to stdout before the error
message is written to stderr.
* NEWS: mention this.
* THANKS: add Richard.
3 files changed