* Teach the importer to import any vector type as SIMDN<Scalar>.
Instead of having a known set of vector types, check to see if the
element type conforms to SIMDScalar; if it does, see if we have a
SIMDN defined with the right number of elements. If both are satisfied,
import the vector type as that Swift type.
By making this change, we gain the ability to import vector types
that aren't defined in terms of the Darwin simd module, which lets
us use C API with vector types on other platforms. It also lets us
import *every* vector type that Swift can represent, rather than the
small subset that are currently hardcoded.
* Increased test coverage for increased SIMD types that we can import.
Includes some minor cleanup from review. Also eliminates the old
simd_sans_simd test, since we can now import all of these types even when the simd module isn't imported.
Share the code that does elementwise coercions, which already behaved correctly, with the code that does struct-to-struct coercions, which still had the overly-conservative constraint. Fixes rdar://problem/21294916.
Swift SVN r29399
When -enable-simd-import is active, if we encounter a vector type, try to load the SIMD Swift module, and if successful, map float, double, and int vectors to SIMD.{Float,Double,Int}N types if they exist.
Swift SVN r27367
