test/Maketests (clos1way): Set AC_ALL=C, since clos1way.awk no longer does.
Addition in TODO.
Doc update for isarray.
Merge remote-tracking branch 'origin/gawk-4.1-stable' into gawk-4.1-stable
Fix inconsistency in system vs pipes in non-socket Windows builds.

 io.c: Move #include "popen.h" out of the HAVE_SOCKETS condition,
 as this is needed for non-sockets builds as well.  See
 http://lists.gnu.org/archive/html/bug-gawk/2013-06/msg00014.html
 for the details of the problem this caused.
Move clos1way test into Makefile.am.
Fix multibyte character problem with brackets in dfa.c.
Doc fix with texinfo.tex.
Add helpers/ChangeLog, update in testdfa.c.
New test case for dfa problem fixed earlier.
Minor cleanup in awkgram.y.
Bug fix in profile.c:pp_string for valgrind.
Update in README_d/README.pc.
Fix a typo in test/ChangeLog.
Fix for %c in multibyte locale + new tests.
Force array indices to be strings in flatten_array API.
Make min be MIN.
Minor update in TODO.
Fix compiling on MinGW.
Updated TODO.