account for different versions of i2c-dev installed on the system

I2C Library/I2C.c

@@ -34,8 +34,19 @@ SOFTWARE.
 #include<stdio.h>
 #include<fcntl.h>
 #include<sys/ioctl.h>
-#include<linux/i2c.h>
-#include<linux/i2c-dev.h>
+#include <linux/i2c-dev.h>
+// heuristic to guess what version of i2c-dev.h we have:
+// the one installed with `apt-get install libi2c-dev`
+// would conflict with linux/i2c.h, while the stock
+// one requires linus/i2c.h
+#ifndef I2C_SMBUS_BLOCK_MAX
+// If this is not defined, we have the "stock" i2c-dev.h
+// so we include linux/i2c.h
+#include <linux/i2c.h>
+typedef unsigned char i2c_char_t;
+#else
+typedef char i2c_char_t;
+#endif
 
 /* Header Files */
 #include "I2C.h"