upnpsoap: fix uninitialized read with emtpy filter
Introduce THISORNUL macro.
Fix various potential illegal access and memory leaks in error conditions.
process: remove logically dead code.
Clean up a couple return value checks.
Fix typo in multi content type example
upnphttp: check realloc return while receiving headers
upnphttp: limit receive headers size to 1 MB
upnphttp: check realloc return while receiving request body
upnphttp: improve robustness against malformed (possibly malicious) requests
Declare printf-like attributes for strcatf() and xasprintf()

Declare printf-like attributes for strcatf() and xasprintf(), and
clean up errors found by the compile after doing so.
Add printf attribute to log_err/DPRINTF and fix a few warnings

Modified to not use %z for portability reasons.
minissdp: fix potential out-of-bounds read
albumart: remove logically dead code
cleanup: avoid dereferencing NULL pointers
cleanup: remove unnecessary sbeacon set
sql: use va_end() where appropriate
utils: add noalloc flag to modifyString()

This should make it more straightforward for code analyzers to
tell if the function is going to allocate memory.
albumart: use a separate variable for temporary pointer storage

Re-using the same one confuses some static code analyzers, and
is a bit less readable.
http: fix error handling in the fallback read/write path