add cortex-v7a support

How To Run:
    see TencentOS-tiny\board\ALPHA_I.MX_emmc_256ddr\README.md

TODO Next:
1. VFP support
2. fault diagnosis support
3. qemu vexpress ca9 support
4. raspberry pi support
5. SMP support

board/ALPHA_I.MX_emmc_256ddr/stdio/include/vsprintf.h

@@ -0,0 +1,46 @@
+/*
+ * Use local definitions of C library macros and functions
+ * NOTE: The function implementations may not be as efficient
+ * as an inline or assembly code implementation provided by a
+ * native C library.
+ */
+
+#include "types.h"
+
+#ifndef va_arg
+
+#ifndef _VALIST
+#define _VALIST
+typedef char *va_list;
+#endif /* _VALIST */
+
+/*
+ * Storage alignment properties
+ */
+#define	 NATIVE_INT		 int
+#define  _AUPBND         (sizeof (NATIVE_INT) - 1)
+#define  _ADNBND         (sizeof (NATIVE_INT) - 1)
+
+/*
+ * Variable argument list macro definitions
+ */
+
+#define _bnd(X, bnd)    (((sizeof (X)) + (bnd)) & (~(bnd)))
+#define va_arg(ap, T)   (*(T *)(((ap) += (_bnd (T, _AUPBND))) - (_bnd (T,_ADNBND))))
+#define va_end(ap)      (void) 0
+#define va_start(ap, A) (void) ((ap) = (((char *) &(A)) + (_bnd (A,_AUPBND))))
+
+#endif /* va_arg */
+
+unsigned long simple_strtoul(const char *cp,char **endp,unsigned int base);
+long simple_strtol(const char *cp,char **endp,unsigned int base);
+unsigned long long simple_strtoull(const char *cp,char **endp,unsigned int base);
+long long simple_strtoll(const char *cp,char **endp,unsigned int base);
+//static int  skip_atoi(const char **s);
+//char * number(char * buf, char * end, long long num, int base, int size, int precision, int type);
+int vsnprintf(char *buf, size_t size, const char *fmt, va_list args);
+int snprintf(char * buf, size_t size, const char *fmt, ...);
+int vsprintf(char *buf, const char *fmt, va_list args);
+int sprintf(char * buf, const char *fmt, ...);
+int vsscanf(const char * buf, const char * fmt, va_list args);
+int sscanf(const char * buf, const char * fmt, ...);