stdlib: broaden ucrt module

Add `process` to the ucrt module as this is used in the Foundation port
for Windows.

Author: compnerd

stdlib/public/Platform/ucrt.modulemap

@@ -104,6 +104,11 @@ module ucrt [system] {
     }
   }
 
+  module process {
+    header "process.h"
+    export *
+  }
+
   module corecrt {
     header "corecrt.h"
     export *
@@ -112,6 +117,11 @@ module ucrt [system] {
       header "corecrt_io.h"
       export *
     }
+
+    module math {
+      header "corecrt_math.h"
+      export *
+    }
   }
 }