Fix I/O suspension. This little nugget of code was introduced in r30 as part of...

Fix I/O suspension.  This little nugget of code was introduced in r30 as part of an early attempt to make buffered I/O work with the optimized Huffman codec.  Ultimately, r32 reverted a lot of that mess and introduced much of the logic we now use, rendering this code unnecessary, but it was never reverted because it only causes problems when I/O suspension is used, and apparently no one has tried to do that with libjpeg-turbo until now.

git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@954 632fc199-4ca6-4c93-a231-07263d6284db