[Issue 19194] New: version for `-mscrtlib` specification

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19194

          Issue ID: 19194
           Summary: version for `-mscrtlib` specification
           Product: D
           Version: D2
          Hardware: All
                OS: Windows
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: turkeyman at gmail.com

The MSCRT libs have data structures appearing in the ABI which are defined
differently for each build of the lib.

Please create a builtin version which is defined for each selection of
`-mscrtlib` so code can detect and match the data structures from the lib.


*** Splitting https://issues.dlang.org/show_bug.cgi?id=18999 for simplicity

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