Do not export SkTDArray when building Skia as a DLL

This class has four members (deleteAll, freeAll, unrefAll and
safeUnrefAll) which will only compile for certain instantiations of
SkTDArray depending on the template argument type.  Marking this class
as dllexport breaks the build with clang-cl because of
http://llvm.org/PR20163.  Since this class is header-only, we can just
make it non-exported to enable building Skia as a DLL with clang-cl.

BUG=skia:
R=ctguil@chromium.org, mtklein@google.com, reed@google.com

Author: ehsan.akhgari@gmail.com

Review URL: https://codereview.chromium.org/368253002

AUTHORS

@@ -13,6 +13,7 @@
 
 ACCESS CO., LTD. <*@access-company.com>
 ARM <*@arm.com>
+Ehsan Akhgari <ehsan.akhgari@gmail.com>
 George Wright <george@mozilla.com>
 Google Inc. <*@google.com>
 Igalia <*@igalia.com>

include/core/SkTDArray.h

@@ -12,7 +12,7 @@
 
 #include "SkTypes.h"
 
-template <typename T> class SK_API SkTDArray {
+template <typename T> class SkTDArray {
 public:
     SkTDArray() {
         fReserve = fCount = 0;