zstd: update to 1.3.2

v1.3.2
new : long range mode, using --long command
new : ability to generate and decode magicless frames
changed : maximum nb of threads reduced to 200, to avoid address space exhaustion in 32-bits mode
fix : multi-threading compression works with custom allocators
fix : ZSTD_sizeof_CStream() was over-evaluating memory usage
fix : a rare compression bug when compression generates very large distances and bunch of other conditions (only possible at --ultra -22)
fix : 32-bits build can now decode large offsets (levels 21+)
cli : added LZ4 frame support by default
cli : improved --list output
cli : new : can split input file for dictionary training, using command -B#
cli : new : clean operation artefact on Ctrl-C interruption
cli : fix : do not change /dev/null permissions when using command -t with root access
cli : fix : write file size in header in multiple-files mode
api : added macro ZSTD_COMPRESSBOUND() for static allocation
api : experimental : new advanced decompression API
api : fix : sizeof_CCtx() used to over-estimate
build: fix : no-multithread variant compiles without pool.c dependency
build: better compatibility with reproducible builds
example : added streaming_memory_usage
license : changed /examples license to BSD + GPLv2
license : fix a few header files to reflect new license

(adam)