[clang] [Modules] Don't assume an overriden module file can not be out-of-date

There is an assertion in ModuleFile assumes that an overriden module
file can't be out of date. But it is not seriously true in the case
clangd. e.g., the source files are overriden, but clangd relies on if
the files are out of date to trigger rebuilding preamble.

And techniquely, overriden doesn't imply it can't be out of date. This
was found during the use clangd of a large code base with modules.
Although I failed to reproduce an example, I feel it is fine to land
this directly for this particular case.

Author: ChuanqiXu9

clang/include/clang/Serialization/ModuleFile.h

@@ -88,13 +88,13 @@ class InputFile {
 
   InputFile(FileEntryRef File, bool isOverridden = false,
             bool isOutOfDate = false) {
-    assert(!(isOverridden && isOutOfDate) &&
-           "an overridden cannot be out-of-date");
     unsigned intVal = 0;
-    if (isOverridden)
-      intVal = Overridden;
-    else if (isOutOfDate)
+    // Make isOutOfDate with higher priority than isOverridden.
+    // It is possible if the recorded hash value mismatches.
+    if (isOutOfDate)
       intVal = OutOfDate;
+    else if (isOverridden)
+      intVal = Overridden;
     Val.setPointerAndInt(&File.getMapEntry(), intVal);
   }