0024284: Some trivial warnings produced by ICC 14

Eliminated ICC 14 warnings:
# 82: storage class is not first (e.g. "int static f()"
# 2621: attribute "dllexport" does not apply here (e.g. "Standard_EXPORT typedef int qqint;")
# 2415: variable "..." of static storage duration was declared but never referenced
# 111: statement is unreachable (usually "break" after "return" in cycles)

src/PLib/PLib.cxx

@@ -1401,7 +1401,6 @@ void  PLib::EvalPolynomial(const Standard_Real    Par,
       }
     }
     break;
-    break;
   }
   case 15 : {
     *tmpRA = *tmpPA; tmpRA++; tmpPA++;