* gl/lib/mbsalign.c (mbsalign): Ensure the temporary destination buffer
is big enough, as it may need to be bigger than the source buffer
in the presence of single byte non printable chars.
* gl/tests/test-mbsalign.c (main): Add a test to trigger the issue.
* gl/lib/mbsalign.c (mbsalign): Support the MBA_UNIBYTE_FALLBACK
flag which reverts to unibyte mode if one can't allocate memory
or if there are invalid multibyte characters present.
Note memory is no longer dynamically allocated in unibyte mode so
one can assume that mbsalign() will not return an error if this
flag is present. Don't calculate twice, the number of spaces,
when centering. Suppress a signed/unsigned comparison warning.
(ambsalign): A new wrapper function to dynamically allocate
the minimum memory required to hold the aligned string.
* gl/lib/mbsalign.h: Add the MBA_UNIBYTE_FALLBACK flag and
also document others that may be implemented in future.
(ambsalign): A prototype for the new wrapper.
* gl/tests/test-mbsalign.c (main): New test program.
* gl/modules/mbsalign-tests: A new index to reference the tests.
* .x-sc_program_name: Exclude test-mbsalign.c from this check.
* gl/tests/test-argv-iter.c: Move declaration "up", so as not
to ruffle feathers of crufty compilers. We accommodate such
compilers here solely because this module may migrate to gnulib.
Tiny patch by Matthew Woehlke.
Pádraig Brady
Jim Meyering