betterC: string mixins in module - again

[DLearner via Digitalmars-d-learn]

Got a highly reduced example:

The following code works perfectly
```
extern(C) void main() {
   string mxnInit(string parmScrnDef) {
      if(__ctfe) {
         return   `{` ~

                     `enum NoOfScrns = 4;` ~

                     `string [NoOfScrns] ScreenNames;` ~
                     `import core.stdc.stdio : printf; 
printf("NoOfScrns = %d\n", cast(int)(NoOfScrns)); ` ~

                  `}`;
      } else {
         return   ``;
      }
   }

   mixin(mxnInit("NPL4"));
}
```


But split things so that ctfemod contains
```
   string mxnInit(string parmScrnDef) {
      if(__ctfe) {
         return   `{` ~

                     `enum NoOfScrns = 4;` ~

                     `string [NoOfScrns] ScreenNames;` ~
                     `import core.stdc.stdio : printf; 
printf("NoOfScrns = %d\n", cast(int)(NoOfScrns)); ` ~

                  `}`;
      } else {
         return   ``;
      }
   }
```

Called from a master:
```
extern(C) void main() {

   import ctfemod;

   mixin(mxnInit("NPL4"));
}
```

And we get: (DMD64 D Compiler v2.111.0)
```
ctfemst.obj : error LNK2019: unresolved external symbol 
_memset128ii referenced in function main
ctfemst.exe : fatal error LNK1120: 1 unresolved externals
Error: linker exited with status 1120
       C:\Program Files\Microsoft Visual 
Studio\2022\Community\VC\Tools\MSVC\14.41.34120\bin\HostX64\x64\link.exe /NOLOGO "ctfemst.obj"    /LIBPATH:"C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.41.34120\lib\x64" legacy_stdio_definitions.lib /LIBPATH:"C:\Program Files (x86)\Windows Kits\10\Lib\10.0.22000.0\ucrt\x64" /LIBPATH:"C:\Program Files (x86)\Windows Kits\10\lib\10.0.22000.0\um\x64"
Error: undefined reference to `_memset128ii`
       referenced from `main`
       perhaps a library needs to be added with the `-L` flag or 
`pragma(lib, ...)`
```