[Issue 18668] Implement modPow() for std.bigint

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18668

Nathan S. <n8sh.secondary at hotmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |n8sh.secondary at hotmail.com
         Resolution|---                         |FIXED

--- Comment #2 from Nathan S. <n8sh.secondary at hotmail.com> ---
`std.bigint.powMod` was added in version 2.087 but did not appear in the
changelog.

https://github.com/dlang/phobos/commit/e962cc7ec558e2cd097756e585f3edc06db9bcbf

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