debuginfod: PR28034 - No longer escape '/', and loop efficiency

debuginfod: PR28034 - No longer escape '/', and loop efficiency

Previously, urls containing '/', so most urls, would escape '/' to %2F,
which is undesirable for use in other libraries which may escape
differently. This patch escapes the '/' and replaces all of them
ensuring there are no %2Fs sent.
Some inefficiencies within the code were fixed, such as changing constant
operations of a while loop within a for loop to a while loop outside of
a for loop. Also strlen is no longer used within the loop, simplifying
the interior operations to mere arithmetic.

https://sourceware.org/bugzilla/show_bug.cgi?id=28034

Signed-off-by: Noah Sanci <nsanci@redhat.com>