[NFC] Refactor the Preprocessor function that handles Macro definitions and rename Arguments to Parameters in Macro Definitions. 
  - Extracted the reading of the tokens out into a separate function.
  - Replace 'Argument' with 'Parameter' when referring to the identifiers of the macro definition (as opposed to the supplied arguments - MacroArgs - during the macro invocation).

This is in preparation for submitting patches for review to implement __VA_OPT__ which will otherwise just keep lengthening the HandleDefineDirective function and making it less comprehensible.


Thanks!

llvm-svn: 308157
diff --git a/clang/unittests/Lex/LexerTest.cpp b/clang/unittests/Lex/LexerTest.cpp
index a887c22..923aff1 100644
--- a/clang/unittests/Lex/LexerTest.cpp
+++ b/clang/unittests/Lex/LexerTest.cpp
@@ -379,11 +379,11 @@
   auto PP = CreatePP("\"StrArg\", 5, 'C'", ModLoader);
 
   llvm::BumpPtrAllocator Allocator;
-  std::array<IdentifierInfo *, 3> ArgList;
+  std::array<IdentifierInfo *, 3> ParamList;
   MacroInfo *MI = PP->AllocateMacroInfo({});
   MI->setIsFunctionLike();
-  MI->setArgumentList(ArgList, Allocator);
-  EXPECT_EQ(3u, MI->getNumArgs());
+  MI->setParameterList(ParamList, Allocator);
+  EXPECT_EQ(3u, MI->getNumParams());
   EXPECT_TRUE(MI->isFunctionLike());
 
   Token Eof;