[Patch][BZ 6530] *printf and incomplete multibyte sequences returns-1 bogusly

[Jeff Law <law at redhat dot com>]

Attached is the patch I checked in to fix BZ 6530.

As mentioned in the BZ, comment #6 C99 conformance demands:

If no l length modifier is present, the argument shall be a pointer to 
the initial element of an array of character type.246) [...]  If an l 
length modifier is present, the argument shall be a pointer to the 
initial element of an array of wchar_t type.

246) No special provisions are made for multibyte characters.

So a format string such as %.50s, the string must be treated as an array 
of chars.  Returning an error because the string isn't a valid UTF-8 
sequence isn't right according to the standard.

The patch simply removes the unwanted code which tried to treat the 
string like multibyte chars.  The patch to remove the unwanted code is 
originally from Andreas Schwab and we've been using it to avoid this 
problem in Fedora for about two years now.

Jonathan Nieder cobbled together the necessary changes to the testsuite 
to test for this problem.

All I've done is combine those two changes into a single patch along 
with the usual NEWS update.

I verified that Jonathan's test fails when installed without Andreas's 
patch and that after Andreas's patch the test succeeds.  I observed no 
regressions when testing.

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