Platform: further modularise ucrt

Add a couple of submodules for these modules to further modularise the
headers.  This might expose additional APIs now as some of these headers
would not have been indirectly included and wind up in the wrong module.

Author: compnerd

stdlib/public/Platform/ucrt.modulemap

@@ -35,6 +35,11 @@ module ucrt [system] {
       export *
     }
 
+    module float {
+      header "float.h"
+      export *
+    }
+
     module inttypes {
       header "inttypes.h"
       export *
@@ -102,6 +107,11 @@ module ucrt [system] {
           export *
         }
 
+        module timeb {
+          header "sys/timeb.h"
+          export *
+        }
+
         module types {
           header "sys/types.h"
           export *
@@ -120,8 +130,8 @@ module ucrt [system] {
     export *
   }
 
-  module process {
-    header "process.h"
+  module dos {
+    header "dos.h"
     export *
   }
 
@@ -130,6 +140,21 @@ module ucrt [system] {
     export *
   }
 
+  module minmax {
+    header "minmax.h"
+    export *
+  }
+
+  module multibyte {
+    header "mbstring.h"
+    export *
+  }
+
+  module process {
+    header "process.h"
+    export *
+  }
+
   module wchar {
     header "wchar.h"
     export *
@@ -153,11 +178,21 @@ module corecrt [system] {
     export *
   }
 
+  module malloc {
+    header "corecrt_malloc.h"
+    export *
+  }
+
   module math {
     header "corecrt_math.h"
     export *
   }
 
+  module share {
+    header "corecrt_share.h"
+    export *
+  }
+
   module stdio {
     header "corecrt_wstdio.h"
     export *