Mock out mgos_i2c.h to work with Linux.

include/mgos_mock.h

@@ -0,0 +1,35 @@
+#ifndef __MGOS_MOCK_H
+#define __MGOS_MOCK_H
+
+/* Some functions mocked from MGOS, so we can run unit tests standalone.
+ */
+
+#include "mgos.h"
+#include <time.h>
+#include <sys/time.h>
+
+// mgos_log
+enum cs_log_level {
+  LL_NONE = -1,
+  LL_ERROR = 0,
+  LL_WARN = 1,
+  LL_INFO = 2,
+  LL_DEBUG = 3,
+  LL_VERBOSE_DEBUG = 4,
+
+  _LL_MIN = -2,
+  _LL_MAX = 5,
+};
+
+int log_print_prefix(enum cs_log_level l, const char *func, const char *file);
+
+#define LOG(l, x)                                                    \
+  do {                                                               \
+    if (log_print_prefix(l, __func__, __FILE__)) printf x; \
+    printf("\r\n"); \
+  } while (0)
+
+
+float mg_time();
+
+#endif // __MGOS_MOCK_H