[over.literal] Mark use of a reserved identifier with 'error'.

Author: jensmaurer

source/overloading.tex

@@ -4259,7 +4259,7 @@
 float operator ""_e(const char*);                   // OK
 float operator ""E(const char*);                    // error: reserved literal suffix~(\ref{usrlit.suffix}, \ref{lex.ext})
 double operator""_Bq(long double);                  // OK: does not use the reserved identifier \tcode{_Bq}\iref{lex.name}
-double operator"" _Bq(long double);                 // uses the reserved identifier \tcode{_Bq}\iref{lex.name}
+double operator"" _Bq(long double);                 // error: uses the reserved identifier \tcode{_Bq}\iref{lex.name}
 float operator " " B(const char*);                  // error: non-empty \grammarterm{string-literal}
 string operator "" 5X(const char*, std::size_t);    // error: invalid literal suffix identifier
 double operator "" _miles(double);                  // error: invalid \grammarterm{parameter-declaration-clause}