Fix modules build after introduction of PassSupport.h include check

D78815 added a check that ensures that PassSupport.h and PassAnalysisSupport.h
aren't included directly. However, as compiling this header into a module will
try to parse it with a clean preprocessor state, this check is also triggered
there. The check seems to make sense and it seems that compiling this header
into its own module is a mistake, so this patch makes those two headers
textual in the modulemap.

llvm/include/llvm/module.modulemap

@@ -212,8 +212,8 @@ module LLVM_Pass {
     // PassSupport.h and PassAnalysisSupport.h are made available only through
     // Pass.h.
     header "Pass.h"
-    header "PassSupport.h"
-    header "PassAnalysisSupport.h"
+    textual header "PassSupport.h"
+    textual header "PassAnalysisSupport.h"
     export *
   }