Rename some PDB classes.

We have a lot of very similarly named classes related to
dealing with module debug info.  This patch has NFC, it just
renames some classes to be more descriptive (albeit slightly
more to type).  The mapping from old to new class names is as
follows:

   Old          |        New
ModInfo         | DbiModuleDescriptor
ModuleSubstream | ModuleDebugFragment
ModStream       | ModuleDebugStream

With the corresponding Builder classes renamed accordingly.

Differential Revision: https://reviews.llvm.org/D32506

llvm-svn: 301555
diff --git a/llvm/lib/DebugInfo/PDB/Native/DbiStream.cpp b/llvm/lib/DebugInfo/PDB/Native/DbiStream.cpp
index b9f5357..4802cc6 100644
--- a/llvm/lib/DebugInfo/PDB/Native/DbiStream.cpp
+++ b/llvm/lib/DebugInfo/PDB/Native/DbiStream.cpp
@@ -10,9 +10,9 @@
 #include "llvm/DebugInfo/PDB/Native/DbiStream.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
+#include "llvm/DebugInfo/PDB/Native/DbiModuleDescriptor.h"
 #include "llvm/DebugInfo/PDB/Native/ISectionContribVisitor.h"
 #include "llvm/DebugInfo/PDB/Native/InfoStream.h"
-#include "llvm/DebugInfo/PDB/Native/ModInfo.h"
 #include "llvm/DebugInfo/PDB/Native/PDBFile.h"
 #include "llvm/DebugInfo/PDB/Native/RawConstants.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
@@ -252,11 +252,12 @@
   if (ModInfoSubstream.getLength() == 0)
     return Error::success();
 
-  // Since each ModInfo in the stream is a variable length, we have to iterate
+  // Since each DbiModuleDescriptor in the stream is a variable length, we have
+  // to iterate
   // them to know how many there actually are.
   BinaryStreamReader Reader(ModInfoSubstream);
 
-  VarStreamArray<ModInfo> ModInfoArray;
+  VarStreamArray<DbiModuleDescriptor> ModInfoArray;
   if (auto EC = Reader.readArray(ModInfoArray, ModInfoSubstream.getLength()))
     return EC;
   for (auto &Info : ModInfoArray) {
@@ -371,10 +372,12 @@
     NumSourceFiles += Count;
 
   // This is the array that in the reference implementation corresponds to
-  // `ModInfo::FileLayout::FileNameOffs`, which is commented there as being a
+  // `DbiModuleDescriptor::FileLayout::FileNameOffs`, which is commented there
+  // as being a
   // pointer. Due to the mentioned problems of pointers causing difficulty
   // when reading from the file on 64-bit systems, we continue to ignore that
-  // field in `ModInfo`, and instead build a vector of StringRefs and stores
+  // field in `DbiModuleDescriptor`, and instead build a vector of StringRefs
+  // and stores
   // them in `ModuleInfoEx`.  The value written to and read from the file is
   // not used anyway, it is only there as a way to store the offsets for the
   // purposes of later accessing the names at runtime.