Simplify and speed-up ssl_io_data_dump().

Simplify and speed-up ssl_io_data_dump().

Instead of using a temp buffer for each byte or char written, and calling
strlen over and over again to find the place where to copy this buffer,
write directly at the correct place in the final buffer, and take advantage
of 'apr_snprintf' returning the number of bytes copied.

This looks like a hot path when running the test framework (because of TRACE7), so it could be slighly useful in this use case :)

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1880500 13f79535-47bb-0310-9956-ffa450edef68