image: Move HOSTCC image code to tools/

This code is never compiled into U-Boot, so move it into a separate
file in tools/ to avoid the large #ifdef.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Marek Vasut <marex@denx.de>

include/image.h

@@ -636,6 +636,9 @@ void fit_conf_print(const void *fit, int noffset, const char *p);
 int fit_check_ramdisk(const void *fit, int os_noffset,
 		uint8_t arch, int verify);
 
+int calculate_hash(const void *data, int data_len, const char *algo,
+			uint8_t *value, int *value_len);
+
 #ifndef USE_HOSTCC
 static inline int fit_image_check_target_arch(const void *fdt, int node)
 {