onigmo: windows: Use CMake when using MSVC

[cosmo0920]

onigmo-cmake/CMakeLists.txt's original license is LGPL-2.0.
Can we include this LGPL-2.0-ed license file?
Is there any lincense incompatibility?

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When we use MSVC, we cannot execute configure, autoconf, and make.
Instead, we should generate Visual Studio solution files via cmake.

Signed-off-by: Hiroshi Hatake [email protected]

[cosmo0920]

Related: #960

[fujimotos]

We had some office discussion about this patch with @kou.

The overall conclusion was that we are better to submit this patch to
the upstream (onigmo) project, instead of maintaining a custom build
file by our hand in this repo.

@cosmo0920 Can you handle this patch as kou suggested next week?
(prob #991 too)

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Side Note There's yet another way to build onigomo, which does not
require a custom build file, so the policy mentioned above should pose
no issue to the overall dev schedule.

We'll switch to the new build file once the upstream integrates it!