Coding style fixup for PR 2500.

As requested by Andrei.
Wholesale coding style fix for std.numeric.
Don't use built-in .sort in std.string.abbrev()

This also makes it CTFE-able. Yay!
Make std.file.mkdir safe
Fix issue 13535 byCodeUnit doesn't satisfy hasSlicing
Merge pull request #2559 from quickfur/abbrev_sort

Don't use built-in .sort in std.string.abbrev()
Merge pull request #2563 from sinkuu/bycodeunit_slice

Fix issue 13535 byCodeUnit doesn't satisfy hasSlicing
Fill in ARM FPSCR stub
Merge pull request #2564 from ibuclaw/armfpscr

Fill in ARM FPSCR stub in std.math
Use std.windows.syserror.wenforce instead of cenforce on Windows
Merge pull request #2552 from quickfur/sumOfLogs_fixup

Coding style fixup for PR 2500.
Don't use built-in .sort in std.base64 unittests
Preemptive fix of other places where .sort is used
Merge pull request #2565 from quickfur/std_base64_sort

Don't use built-in .sort in std.base64 and other places
Fix the documentation for mkdir
workaround inline Issue 7625

- add explicit else branches so that dmd can inline those functions
Fix the arguments for std.windows.syserror.wenforce
Merge pull request #2566 from MartinNowak/workaround7625

workaround inline Issue 7625
attributes for inline asm
Fix 9906: unaryFun and binaryFun should recognize static opCall

Structs or classes with static `opCall` should be recognized as valid
function objects.