Fixed compiler warning

I moved the constant to the enum in order to avoid this:
ext/pgsql/pgsql.c:3491: warning: comparison is always false due to limited range of data type

Works in gcc 4.6, but I'm not sure about other compilers.

Author: mbeccati

ext/pdo/php_pdo_driver.h

@@ -72,11 +72,11 @@ enum pdo_param_type {
 	/* get_col ptr should point to a zval*
 	   and the driver is responsible for adding correct type information to get_column_meta()
 	 */
-	PDO_PARAM_ZVAL
-};
+	PDO_PARAM_ZVAL,
 
-/* magic flag to denote a parameter as being input/output */
-#define	PDO_PARAM_INPUT_OUTPUT 	0x80000000	
+	/* magic flag to denote a parameter as being input/output */
+	PDO_PARAM_INPUT_OUTPUT = 0x80000000
+};
 
 #define PDO_PARAM_FLAGS			0xFFFF0000