zlib / zlib-ng licence file

[DimitriPapadopoulos]

File LICENSES/ZLIB.txt covers the vendored internal-complibs/zlib-1.2.11 code, especially after f60e763 / #350.

It is also referred to in this code based from zlib-ng:

c-blosc/blosc/fastcopy.c

Lines 10 to 18 in c9ddc13

	/*********************************************************************
	The code in this file is heavily based on memcopy.h, from the
	zlib-ng compression library. See LICENSES/ZLIB.txt for details.
	See also: https://github.com/Dead2/zlib-ng/blob/develop/zlib.h
	New implementations by Francesc Alted:
	* fast_copy() and copy_run() functions
	* Support for SSE2/AVX2 copy instructions for these routines
	**********************************************************************/

I suggest you add a LICENSES/ZLIB-NG.txt file for clarity.

I can submit a merge request if you agree.

[DimitriPapadopoulos]

Note that there is no file memcopy.h in current zlib-ng sources. The relevant code has been moved to architecture-dependent files under develop/arch starting with zlib-ng/zlib-ng@e40d88a.

[DimitriPapadopoulos]

Fixed by #356.