Remove useless error check for bin2hex()

And change prototype accordingly...

Closes GH-4550.

Author: Girgias

ext/standard/string.c

@@ -223,7 +223,7 @@ PHP_MSHUTDOWN_FUNCTION(localeconv)
 /* }}} */
 #endif
 
-/* {{{ proto string|false bin2hex(string data)
+/* {{{ proto string bin2hex(string data)
    Converts the binary representation of data to hex */
 PHP_FUNCTION(bin2hex)
 {
@@ -236,10 +236,6 @@ PHP_FUNCTION(bin2hex)
 
 	result = php_bin2hex((unsigned char *)ZSTR_VAL(data), ZSTR_LEN(data));
 
-	if (!result) {
-		RETURN_FALSE;
-	}
-
 	RETURN_STR(result);
 }
 /* }}} */