swift234

Drive the semantic wedge harder into lvalues.  Now, instead of having one LValueType
with qualifiers on it, we have two distinct types:
 - LValueType(T) aka @lvalue T, which is used for mutable values on the LHS of an
   assignment in the typechecker.
 - InOutType(T) aka @inout T, which is used for @inout arguments, and the implicit
   @inout self argument of mutable methods on value types.  This type is also used
   at the SIL level for address types.

While I detangled a number of cases that were checking for LValueType (without checking
qualifiers) and only meant @inout or @lvalue, there is more to be done here.  Notably,
getRValueType() still strips @inout, which is totally and unbearably wrong.



Swift SVN r11727