Fix comment style

Author: adambaratz

ext/pdo_dblib/php_pdo_dblib_int.h

@@ -90,8 +90,9 @@ typedef unsigned char *LPBYTE;
 typedef float			DBFLT4;
 #endif
 
-// hardcoded string length from FreeTDS
-// src/tds/convert.c:tds_convert_datetimeall()
+/* hardcoded string length from FreeTDS
+ * src/tds/convert.c:tds_convert_datetimeall()
+ */
 # define DATETIME_MAX_LEN   63
 
 int pdo_dblib_error_handler(DBPROCESS *dbproc, int severity, int dberr,