Trailing whitespace stripped by autoconf

[Tim Van Holder]

Not sure if this has been reported yet.

While testing a patch to gcc's configure.in, I found that a configure
script generated by cvs autoconf (2.57a) always resulted in a failed
test.  The configure script uses

                cat > conftest.big <<EOF
  0000 00000010 00000000 017a0001 781a0004  .........z..x...
  0010 00000001 00000012 00000018 00000000  ................
  0020 00000008 04000000 0844               .........D      
 EOF

to create a few files, then runs objdump on a compiled object
and compares the last three lines to these files.  As such, the six
spaces after the last 'D' are significant, as they are also generated
by objdump.
Now it seems that cvs autoconf trims trailing whitespace, resulting
in incorrected test files; even surrounding the spaces with a single
set of [] didn't help.
This is a regression, as autoconf 2.13 DTRT here.