In the CopyNativeVertexData template function, in the else clause
use memcpy/memset rather than for loops.  This is a performance
improvment for floating point versions of CopyNativeVertexData,
particularly on 32-bit Firefox, where the -arch:IA32 compiler
option used cause the compiler to generate fld/fstp operations
inside the for loops.

Update AUTHORS & CONTRIBUTORS to include AMD.

BUG=angleproject:1317

Change-Id: I7133fc476028284f56783f4e2f9e2395f6227514
Reviewed-on: https://chromium-review.googlesource.com/327590Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>