use O(1) pragmas instead of O(N) attributes

Both Clang and GCC now have ways to set a target attribute
using a pragma for a section of code.   We can do this for
the extra x86 Haswell slice.  skcms.o stay identical.

Change-Id: I07d76df1aac71b166254e02ac9139508513ca2ee
Reviewed-on: https://skia-review.googlesource.com/150962
Auto-Submit: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
2 files changed