Avoid symbol collision with in-kernel zstdlib

For Linux, when zfs is compiled as an in kernel static variant
and the in kernel zstd library is compiled statically into the kernel
a symbol collision will occur. This wrapper header renames all
of the relevant zstd functions to avoid this problem.

Reviewed-by: Kjeld Schouten <kjeld@schouten-lebbing.nl>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Sebastian Gottschall <s.gottschall@dd-wrt.com>
Closes #10775