redefinition of i2c objects in linux.

We run into the following issue when trying to compile in linux.
One workaround is to remove libi2c-dev, but it seems the issue is the way it includes i2c-dev.h and i2c.h.
switchtec-user# make
  CC    lib/platform/linux-i2c.c
In file included from lib/platform/linux-i2c.c:46:0:
/usr/include/linux/i2c-dev.h:37:8: error: redefinition of 'struct i2c_msg'
 struct i2c_msg {
        ^
In file included from lib/platform/linux-i2c.c:45:0:
/usr/include/linux/i2c.h:68:8: note: originally defined here
 struct i2c_msg {
        ^
In file included from lib/platform/linux-i2c.c:46:0:
/usr/include/linux/i2c-dev.h:90:7: error: redefinition of 'union i2c_smbus_data'
 union i2c_smbus_data {
       ^
In file included from lib/platform/linux-i2c.c:45:0:
/usr/include/linux/i2c.h:129:7: note: originally defined here
 union i2c_smbus_data {
       ^
lib/platform/linux-i2c.c: In function 'i2c_msg_pec':
lib/platform/linux-i2c.c:87:14: warning: pointer targets in passing argument 1 of 'crc8' differ in signedness [-Wpointer-sign]
  return crc8(msg->buf, byte_count, pec, false);
              ^
In file included from lib/platform/linux-i2c.c:28:0:
lib/platform/../crc.h:34:9: note: expected 'uint8_t * {aka unsigned char *}' but argument is of type 'char *'
 uint8_t crc8(uint8_t *msg_ptr, uint32_t byte_cnt, uint32_t oldchksum,
         ^
lib/platform/linux-i2c.c: In function 'i2c_gas_cap_get':
lib/platform/linux-i2c.c:224:14: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
  msgs[0].buf = &command_code;
              ^
lib/platform/linux-i2c.c:228:14: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
  msgs[1].buf = rx_buf;
              ^
lib/platform/linux-i2c.c: In function 'i2c_gas_data_write':
lib/platform/linux-i2c.c:303:10: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
  msg.buf = (uint8_t *)i2c_data;
          ^
lib/platform/linux-i2c.c: In function 'i2c_gas_write_status_get':
lib/platform/linux-i2c.c:340:14: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
  msgs[0].buf = &command_code;
              ^
lib/platform/linux-i2c.c:344:14: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
  msgs[1].buf = rx_buf;
              ^
lib/platform/linux-i2c.c: In function 'i2c_gas_data_read':
lib/platform/linux-i2c.c:470:14: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
  msgs[0].buf = (uint8_t *)read_command;
              ^
lib/platform/linux-i2c.c:475:14: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
  msgs[1].buf = (uint8_t *)read_response;
              ^
lib/platform/linux-i2c.c: At top level:
cc1: warning: unrecognized command line option '-Wno-initializer-overrides'
Makefile:114: recipe for target 'build/lib/platform/linux-i2c.o' failed
make: *** [build/lib/platform/linux-i2c.o] Error 1
Microsemi / switchtec-user

redefinition of i2c objects in linux. #221
