!17 重新修正CHAR定义冲突

Merge pull request !17 from Caoruihong/master

kernel/src/stdio/vfprintf.c

 #include "stdio_impl.h"
 #include <errno.h>
 #include <ctype.h>
-/* Undef the CHAR macro definition in los_typedef.h to avoid conflicts with the following CHAR */
-#define CHAR _CHAR
 #include <limits.h>
-#undef CHAR
 #include <string.h>
 #include <stdarg.h>
 #include <stddef.h>
@@ -32,6 +29,10 @@
 
 #define FLAGMASK (ALT_FORM|ZERO_PAD|LEFT_ADJ|PAD_POS|MARK_POS|GROUPED)
 
+/* Redefine the CHAR type that defined in los_typedef.h and introduced
+ * in by limit.h to avoid conflicts with the following enum definition. */
+#define CHAR _CHAR
+
 /* State machine to accept length modifiers + conversion specifiers.
  * Result is 0 on failure, or an argument type to pop on success. */