Update ucrt.modulemap for Windows SDK 10.0.26100

[Steelskin]

• Explanation:
  Windows SDK 10.0.26100 added an include to compiler intrinsics headers in wchar.h. In turn, these headers include malloc.h, stdlib.h and stddef.h from ucrt, this leads to a cyclic dependency between the ucrt and compiler intrinsics modules. Furthermore, Clang 19 (from Swift 6.1) intrinsics headers sometimes clash with the ucrt headers dependencies.
  These changes separate the problematic headers into different standalone modules.
• Scope:
  The changes are limited to ucrt.modulemap, and should be backward-compatible with older Windows SDK versions.
• Issues:
  • New error building for Windows: cyclic dependency in module 'ucrt': ucrt -> _visualc_intrinsics -> ucrt compnerd/swift-build#909
  • Compilation error when trying to compile a simple plugin with Windows SDK 10.0.26100.0 #79745
• Original PRs:
  Update ucrt.modulemap for Windows SDK 10.0.26100 #79751
  Restore legacy_stdio_definitions in ucrt.modulemap #80151
  Put float and stddef back inside the ucrt module #80200
• Risk:
  Very low.
• Testing:
  Local testing with simple projects including the ucrt module with the new module map.
• Reviewers:
  @compnerd

[compnerd]

@swift-ci please smoke test

[Steelskin]

For future reference, this is the failure:

C:\Users\swift-ci\jenkins\workspace\swift-PR-windows\yams\Sources\Yams\Representer.swift:321:45: error: cannot find 'DBL_DECIMAL_DIG' in scope
319 |         // Since `NumberFormatter` creates a string with insufficient precision for Decode,
320 |         // it uses with `String(format:...)`
321 |         let string = String(format: "%.*g", DBL_DECIMAL_DIG, self)
    |                                             `- error: cannot find 'DBL_DECIMAL_DIG' in scope
322 |         // "%*.g" does not use scientific notation if the exponent is less than –4.
323 |         // So fallback to using `NumberFormatter` if string does not uses scientific notation.

[compnerd]

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[compnerd]

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[compnerd]

@swift-ci please smoke test Linux platform

[compnerd]

@swift-ci please smoke test Linux platform

[shahmishal]

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[shahmishal]

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