Split isFromMainFile into two functions.

Basically, isInMainFile considers line markers, and isWrittenInMainFile
doesn't.  Distinguishing between the two is useful when dealing with
files which are preprocessed files or rewritten with -frewrite-includes
(so we don't, for example, print useless warnings).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188968 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/Sema.cpp b/lib/Sema/Sema.cpp
index 26f2631..6cc596c 100644
--- a/lib/Sema/Sema.cpp
+++ b/lib/Sema/Sema.cpp
@@ -722,7 +722,7 @@
           else {
             if (FD->getStorageClass() == SC_Static &&
                 !FD->isInlineSpecified() &&
-                !SourceMgr.isFromMainFile(
+                !SourceMgr.isInMainFile(
                    SourceMgr.getExpansionLoc(FD->getLocation())))
               Diag(DiagD->getLocation(), diag::warn_unneeded_static_internal_decl)
                 << DiagD->getDeclName();
@@ -743,7 +743,7 @@
         if (DiagD->isReferenced()) {
           Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
                 << /*variable*/1 << DiagD->getDeclName();
-        } else if (getSourceManager().isFromMainFile(DiagD->getLocation())) {
+        } else if (SourceMgr.isInMainFile(DiagD->getLocation())) {
           // If the declaration is in a header which is included into multiple
           // TUs, it will declare one variable per TU, and one of the other
           // variables may be used. So, only warn if the declaration is in the