Fix Doxygen issues:

* wrap code blocks in \code ... \endcode;
* refer to parameter names in paragraphs correctly (\arg is not what most
  people want -- it starts a new paragraph);
* use \param instead of \arg to document parameters in order to be consistent
  with the rest of the codebase.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163902 91177308-0d34-0410-b5e6-96231b3b80d8

lib/MC/MCSymbol.cpp

@@ -26,7 +26,7 @@ static bool isAcceptableChar(char C) {
   return true;
 }
 
-/// NameNeedsQuoting - Return true if the identifier \arg Str needs quotes to be
+/// NameNeedsQuoting - Return true if the identifier \p Str needs quotes to be
 /// syntactically correct.
 static bool NameNeedsQuoting(StringRef Str) {
   assert(!Str.empty() && "Cannot create an empty MCSymbol");