Cycles: Restore cycles_cubin_cc to working order

Reviewed by: brecht pmoursnv
Differential Revision: https://developer.blender.org/D7136

Cycles/Optix: Add CYCLES_OPTIX_TEST override

This works similarly to the CYCLES_OPENCL_TEST
environment variable to allow testing on unsupported
hardware.

Note: like the OPENCL test override, this is
for *testing* only and bug reports on unsupported
hardware will *not* be accepted at this point in
time.

Windows/Cleanup: Remove VS2015 support from make.bat

VS2015 has not been supported for a while now but make.bat
still had some support for it.

OpenCL: Bring back CYCLES_OPENCL_TEST override

Back in 2.79 you could either use the debug panel or an
environment variable to override using OpenCL for unsupported
hardware. Which was rather useful for developers when testing
on NVidia just to be sure the CL kernels at-least build properly.

This broke in rB949ab753bb2

This diff restores testing though the CYCLES_OPENCL_TEST
environment variable.

Differential Revision: https://developer.blender.org/D7202

Reviewers: brecht

Cleanup: Prepare for sorted headers on windows

To prepare for D6811 small changes were needed.
we can no longer undefine near/far since the windows
headers use those extensively.

some of the imbuf files need to include the windows
headers explicitly to make sure it builds.

Cleanup: 64 bit file IO on windows.

Unlike Linux where fseek/tell will be either 32 or 64 bit
depending on the target platform, it will always be 32 bit
on windows.

We had some macro magic in BLI_winstuff.h that substituted
them for 64 bit versions, but that is upsetting the system
headers if they get included after BLI_winstuff.h which
is problematic for D6811.

This diff adds proper functions in blenlib and updates
all calls that were using the BLI_winstuff.h header to
gain 64 bit file IO.

note: Anything that was using the 32 bit versions (ie not
including BLI_winstuff.h) will still be using the 32 bit
versions, which is perhaps a good code quality Friday project.

Differential Revision: https://developer.blender.org/D7160

Reviewers: brecht dfelinto

Cleanup: Fix build warnings on windows.

Two headers define the _USE_MATH_DEFINES symbol now, if both
are included warnings are generated.

Added some guards, all good again.

Cleanup: Resolve HKEY conflict

Both the MS headers and blender headers define the HKEY
which gives all kind of inclusion order issues.

This diff renames all *KEY constants to EVT_*KEY to resolve
this conflict.

Reviewed By: brecht , dfelinto

Differential Revision: http://developer.blender.org/D7164

Cleanup: Fix warnings about function signature of register pass

RE_engine_register_pass is sometimes in the headers with type
as an integer parameter, sometimes as eNodeSocketDatatype.

This caused warnings, the root cause was makesrna was not able
to generate the proper type for enums and defaulted to int.

makesrna has been extended with the RNA_def_property_enum_native_type
that allows telling makesrna the native type of an enum, if set it
will be used otherwise it will still fall back to int.

Differential Revision: https://developer.blender.org/D7117

Reviewed By: brecht

Windows: Clean-up warnings originating from bullet

Bullet currently generates the majority of the warnings
on windows all of them are silly. This patch disables
all warns from bullet for now.

We should revisit this if/when we update bullet
to a newer version.

Reviewed By: sergey brecht

Differential Revision: https://developer.blender.org/D7118