add sleef prefix to cmake options.

[xuhancn]

I'm work on enable sleef on pytorch Windows version, and have some build option issue when second build. Error as below:

I read the pytorch cmake file and found that, sleef build options "BUILD_SHARED_LIBS" and "BUILD_TESTS" was conflict to pytorch.
Current pytorch save and restore build options to cmake cache and workarround it.
Save: https://github.com/pytorch/pytorch/blob/cee16353db384dd33a4804f9f26829cacfcfbab7/aten/src/ATen/CMakeLists.txt#L424-L440
Restore: https://github.com/pytorch/pytorch/blob/cee16353db384dd33a4804f9f26829cacfcfbab7/aten/src/ATen/CMakeLists.txt#L480-L485
When secound build the cache will have unexpected behavior and lost some build options, and then different build option will occurred issues.

A good example is MSFT mimalloc. Its build options has its prefix and will not conflict to others: https://github.com/microsoft/mimalloc/blob/master/CMakeLists.txt#L7-L34
Its caller like this: https://github.com/pytorch/pytorch/blob/cee16353db384dd33a4804f9f26829cacfcfbab7/CMakeLists.txt#L1061-L1067

I have tried to add sleef prefix to its cmake files. After this PR, It will help me to enable sleef on pytorch Windows.

[xuhancn]

@blapie Please review this PR. Thanks.

[xuhancn]

Local test.

[blapie]

Hi! Good initiative. Is there a reason for not putting SLEEF_ as a prefix in options starting with BUILD_?
This is a relatively significant change for users, therefore I cannot guarantee this is going to be part of the 3.6 release, unless there is a good reason for it, I'll let you know.

[xuhancn]

Hi! Good initiative. Is there a reason for not putting SLEEF_ as a prefix in options starting with BUILD_? This is a relatively significant change for users, therefore I cannot guarantee this is going to be part of the 3.6 release, unless there is a good reason for it, I'll let you know.

Updated all build options, and let then start with "SLEEF_".

[blapie]

Would be good to do the same for the rest of the cmake variables. There are a bunch in docs/build-with-cmake.md and most of them are defined in Configure.cmake.

[xuhancn]

Would be good to do the same for the rest of the cmake variables. There are a bunch in docs/build-with-cmake.md and most of them are defined in Configure.cmake.

Done.

[blapie]

Just a remark. BUILD_SHARED_LIBS is a standard cmake variable. It seems that SLEEF did overwrite it, which is not recommended.
Renaming sounds like a good idea since the effect of this option seem to differ slightly from the standard, and implement its own custom rules (#132). Namely if SLEEF_BUILD_SHARED_LIBS is ON (default) then we generate shared libraries for all targets, otherwise we don't except for libsleefgnuabi that is always a shared library.
However, if we rename the variable then both options (SLEEF_BUILD_SHARED_LIBS and BUILD_SHARED_LIBS) might need to match.
The other option is to simply delete the redefinition of BUILD_SHARED_LIBS in Sleef and keep the standard name.

option(BUILD_SHARED_LIBS "Build shared libs" ON)

[blapie]

We think this option should be removed altogether and we should keep using the standard cmake variable BUILD_SHARED_LIBS in the rest of the build system. This way we ensure consistency with projects using SLEEF.
Remember that even if turned off libsleefgnuabi will be a shared library.

[xuhancn]

if not set SLEEF_BUILD_SHARED_LIBS , and then use BUILD_SHARED_LIBS ? let SLEEF_BUILD_SHARED_LIBS overwrite BUILD_SHARED_LIBS?

[blapie]

Please rename all SLEEF_BUILD_SHARED_LIBS to BUILD_SHARED_LIBS, then remove this line

option(BUILD_SHARED_LIBS "Build shared libs" ON)

[xuhancn]

Done.

Please rename all SLEEF_BUILD_SHARED_LIBS to BUILD_SHARED_LIBS, then remove this line

option(BUILD_SHARED_LIBS "Build shared libs" ON)

[blapie]

These also would need prefixing.

[xuhancn]

Done.

[blapie]

Thank you! This is looking good, will merge. Thank you for your contribution.