Improved a comment

Author: gribozavr

lib/ClangImporter/ImportDecl.cpp

@@ -3349,7 +3349,7 @@ namespace {
         auto member = Impl.importDecl(nd, getActiveSwiftVersion());
         if (!member) {
           if (!isa<clang::TypeDecl>(nd) && !isa<clang::FunctionDecl>(nd)) {
-            // We don't know what this field is.
+            // We don't know what this member is.
             // Assume it may be important in C.
             hasUnreferenceableStorage = true;
             hasMemberwiseInitializer = false;