Remove use of builtin comma operator.

Cleanup for upcoming Clang warning -Wcomma.  No functionality change intended.

llvm-svn: 261271
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index 43bd12f..d0e38a4 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -719,7 +719,9 @@
   while (Lexer::isObviouslySimpleCharacter(*TokPtr)) {
     if (CharNo == 0)
       return TokStart.getLocWithOffset(PhysOffset);
-    ++TokPtr, --CharNo, ++PhysOffset;
+    ++TokPtr;
+    --CharNo;
+    ++PhysOffset;
   }
   
   // If we have a character that may be a trigraph or escaped newline, use a