1.0.28.51: better MAKE-ARRAY transforms

1.0.28.51: better MAKE-ARRAY transforms

 * Add a source transform for MAKE-ARRAY that declaims LIST and VECTOR
   as NOTINLINE, so the the MAKE-ARRAY deftransforms are able to pick
   them apart (for DIMENSIONS and :INITIAL-CONTENTS.)

 * INITIALIZE-VECTOR is a new magic function with a IR2-CONVERT
   transform. It's purpose is to allow open coding :INITIAL-CONTENTS
   initialization without inhibiting stack allocation.

 * Turns out that making stack allocation decisions during locall
   analysis is not enough since optimization iterates: if a transform
   occurs and introduces new LVARs that would be good for DX after
   the locall analysis has run for the combination, the new LVARs
   will not get their share of stacky goodness. Therefore, after
   a transform propagate DX information to the new functional
   explicitly (see MAYBE-PROPAGATE-DYNAMIC-EXTENT.)

 * The new logic is in TRANSFORM-MAKE-ARRAY-VECTOR, which handles
   all the cases of vector allocation with a known element type:

   ** :INITIAL-CONTENTS (LIST ...), (VECTOR ...) and (BACKQ-LIST ...)
      are picked apart when the length matches the vector length,
      and their arguments are spliced into the call.

      Constant :INITIAL-CONTENTS is picked apart as well.

      Initialization is done using INITIALIZE-VECTOR.

   ** Otherwise :INITIAL-CONTENTS is splatted in place using
      REPLACE after we have checked that the length matches.

   ** :INITIAL-ELEMENT not EQL to the default element uses
      FILL.

   ** Otherwise the default initialization is fine.

   Some additional hair here, since MAYBE-PROPAGATE-DYNAMIC-EXTENT
   cannot deal with OPTIONAL-DISPATCH functionals. So to ensure we get
   full benefit of it, make sure the lambdas we transform to have only
   required arguments -- courtesy of new ELIMINATE-KEYWORD-ARGUMENT
   utility. (Note: it might be worth it to do something like this for
   many cases automatically, to reduce the number of lambdas the
   compiler generates. For inline lambdas we could do the whole &key
   handling _before_ the lambda is converted...)

 * Identify the case of (LIST N) as dimensions as being a vector,
   and delegate to TRANSFORM-MAKE-ARRAY-VECTOR.

 * More efficient allocation of simple multidimensional arrays in
   the presence of :INITIAL-CONTENTS (still slow, though) and
   :INITIAL-ELEMENT (not bad.)

 * Fix the source transform for VECTOR so that it too can stack
   allocate.

 * Updates tests and docs.