Fixed faulty boolean logic

This is a trivial logic error. The "abort" condition would be followed only if `c == 0` with other clauses having no effect.

Author: mattgallagher

lib/Demangling/Demangler.cpp

@@ -1397,7 +1397,7 @@ std::string Demangler::demangleBridgedMethodParams() {
 
   while (!nextIf('_')) {
     auto c = nextChar();
-    if (!c && c != 'n' && c != 'b')
+    if (c != 'n' && c != 'b')
       return std::string();
     Str.push_back(c);
   }