When trying to detect the content type of the

When trying to detect the content type of the
uncompressed content it is often not enough
to read the same number of bytes, we already
read compressed. Since uncompress() allocates a
new buffer, we can increase the number of bytes
to read to the same size, we use in the case,
where the content isn't compressed.

Furthermore zero-terminate the read data to keep
assumptions consistent with the uncompressed case.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@756683 13f79535-47bb-0310-9956-ffa450edef68