Fix default includes ordering to be `-I. -I$(srcdir) ...' again.

Fix default includes ordering to be `-I. -I$(srcdir) ...' again.

* automake.in (handle_compile): Put -I$(srcdir) before include
paths for config headers, as was done before Automake 1.10, but
keep uniquified list without multiple adjacent spaces.
* doc/automake.texi (Program variables): List include paths
in order.
* NEWS: Mention 1.10 regression.
* tests/stdinc.test: New test.
* tests/Makefile.am: Adjust.
* THANKS: Update.
Report by Kent Boortz.