- remove link to the AMD APP SDK from a share hoster
- update windows/linux documentation

reduce blocking during metric update

fix broken AMD OpenCL compile

fix access uninitialized value

The AMD compiler for OpenCL shipped with the driver 14XX is broken
and can not compile xmr-stak since the monero v8 changes are introduced.

- workaround a simple compare.
- add new device define `OPENCL_DRIVER_MAJOR`

With #1845 a race condition during the telemetry update is solved.
The problem is that the used mutex is blocking all threads from updating the metrics during
the statistics are calculated.

- introduce a mutex per miner thread

fix #1906

If the currency provided by the user is not known by the miner we access an uninitialized value.

Add default values for member of `coinDescription`.

update version to 2.5.0

NVIDIA: support for multiple CUDA libs

Fix logo on Windows

Allow to ship the miner with multiple cuda backends those depends on different driver versions.
This will allow to support Turing/Volta and old Fermi GPU within one release.

- add support to search for the first working CUDA backend
- add some more messages to support better debugging (if a user has some issues)

update documantion

NVIDIA: tweak `get_reciprocal`

- update tuning guide
- update miner usage

- remove helper array to perform division
- tweak `get_reciprocal`

NVIDIA: rename config option `comp_mode` 

fix right bitshift in `amd_bitalign`

CUDA: fix invalid results

The name `comp_mode` for a memoy load pattern if a bad choosen name.
Therefore I changed it to `mem_mode` which also gives use the possibility
to add new mode later if needed.

- rename `comp_mode` to `mem_mode`
- fix documentation

In the current implementation the bit align is using signed integer which results in pulling in
ones in the case the sign bit is set.

- cast to unsigned integer before using bitshift

If `comp_mode` is false the results on a windows platform will be invalid.
The reason for that is that `ulong4` is in windows 16byte and in linux 32byte.

thx @xmrig for finding and solving the issue

fix #1873

Add Ryo sponsorship message

CUDA: select hash function from array

CUDA: use volatile pointer

compatibility and better messages

Add a suggestion to an common line which is shown in the event of an crash under windows.

Add compatibility mode for CUDA to avoid invalid shares.

Use an array  instead of a if cascade to select the hasing function for CUDA.

- add more descriptive messages if memory allocation fails
- add gnu compiler flags: `noexecstack` to support systemd
- handle cases where memroy allocation fails

Co-authored-by: Tony Butler <spudz76@gmail.com>

Use volatile pointer to be sure that the compiler is not caching the values.

CPU: fix logical error

Fix wrong warning about unknown ASM type

OpenCL: fix definition range for unroll

fix crash with monero and strided_index

Strided index 1 is not allowed for cryptonight_v8 and monero.
In the case the dev pool is set to monero and the user tuned there settings for
an other currency the miner will crash if strided index or memChunk is not
fitting the requirement to mine monero.
This PR detects wrong configurations and will set strided index and memChunk to a valid
value but only for cryptonight_v8. The user pool settings will only be changed if monero or
cryptonight_v8 is selected.

Fix two new warnings within new code

fix #1870

- remove zero from the valod definition range for the loop unroll option