`MG_ENABLE_...` macros are not yet renamed because it involves some
logic change: e.g. instead of defining `MG_ENABLE_MQTT`, one should
define `MIOT_ENABLE_MQTT`, which should imply `MG_ENABLE_MQTT` as well.
Macro refactoring is going to be done in another PR.
PUBLISHED_FROM=f8b66d5772846126b94223a729a6bd87897f8de6
So they are distinct from CC3200 projects during import
Also update compiler version (5.2.7 -> 5.2.8)
PUBLISHED_FROM=23834212eb51ad068579726a2870e8e6ae87ab9c