tests/floating_point_test.tpl : Tweak target SNR for alac_24.caf.
WAV : Avoid divide by zero exception.

Found a couple of instances where a value retrieved from an input
file header was used as the denominator in a division. If the
retrieved value is zero it results on a divide by zero error.

Found using the afl (http://lcamtuf.coredump.cx/afl/) fuzzer.
Fix a bunch of input validation issues.

Using the afl (http://lcamtuf.coredump.cx/afl/) fuzzer found a
number of issues where a malformed file could cause the various
file format parsers to go into an infinite loop:

* WAV : 7 cases, one leading to memory exhaustion
* AIFF : 1 case
* CAF : 2 cases
* MAT4 : 2 cases
src/wav_w64.c : Fix heap write overflow.

Heap write could occur if the number of channels is less than the
length of the file's channel map.

Found using the afl (http://lcamtuf.coredump.cx/afl/) fuzzer.
src/wav.c : A bunch more fixes.

* Rename variable dword to chunk_size.
* Use %u specifier instead of %d for chunk lengths.
* Fix two more input validation issues that could lead to an infinite
  loop.
Scripts/static-deps-build.mk : Use flac 1.3.1.

Also improve wgetting of tarballs.
Scripts/static-deps-build.mk : Split configure and build steps.