update to zlib v1.2.12

[elrido]

Released on March 27th, from the release notes:

Version 1.2.12 has these key improvements over 1.2.11:

• Fix a deflate bug when using the Z_FIXED strategy that can result in out-of-bound accesses.
• Fix a deflate bug when the window is full in deflate_stored().
• Speed up CRC-32 computations by a factor of 1.5 to 3.
• Use the hardware CRC-32 instruction on ARMv8 processors.
• Speed up crc32_combine() with powers of x tables.
• Add crc32_combine_gen() and crc32_combine_op() for fast combines.

This includes a fix to mitigate CVE-2018-25032, with as of yet unknown severity.

I've also bumped the used npm modules and on my machine get these results running the benchmark:

Benchmark

• NodeJS: v10.19.0
• OS: Ubuntu 20.04 LTS
• CPU: Intel Core i5 2.3GHz
• Memory: 8GB

## lorem_1mb.txt size: 1000205
wasm x 9.99 ops/sec ±0.94% (29 runs sampled)
pako x 8.73 ops/sec ±4.39% (26 runs sampled)
native x 17.15 ops/sec ±2.37% (46 runs sampled)
Deflate: Fastest is native
## deflated lorem_1mb.txt size: 257012
wasm x 161 ops/sec ±1.16% (80 runs sampled)
pako x 121 ops/sec ±2.02% (77 runs sampled)
native x 254 ops/sec ±1.20% (84 runs sampled)
Inflate: Fastest is native