Item_func_like inherits resolve_type from Item_bool_func2 but does not
have much in common with it's parent since every comparison must be done
as strings. Also the call to set_cmp_func() is unnecesary and results in
an error when comparing temporal types with strings.
This patch fixes this error by overriding resolve_type in
Item_func_like, and by omitting the call to set_cmp_func.

Change-Id: I1cea9d5fcf54f3539016aed4cdb77501a547a5ed