[opencl] Add Fuchsia BUILD.gn to OpenCL-Headers

Make the OpenCL Headers available to Fuchsia components by adding BUILD.gn
file to the OpenCL-Headers repo.

//third-party/OpenCL-Headers

fixes: 88330
Change-Id: I4f200e308f88efa3fde3dc3bd593fe479b92736f
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/github.com/KhronosGroup/OpenCL-Headers/+/604363
Reviewed-by: John Bauman <jbauman@google.com>
diff --git a/BUILD.gn b/BUILD.gn
new file mode 100644
index 0000000..e9645a1
--- /dev/null
+++ b/BUILD.gn
@@ -0,0 +1,42 @@
+# Copyright (c) 2021 The Khronos Group Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+config("opencl_headers_config") {
+  include_dirs = [ "." ]
+}
+
+# OpenCL headers only, no compiled sources.
+source_set("opencl_headers") {
+  sources = [
+    "CL/cl.h",
+    "CL/cl_d3d10.h",
+    "CL/cl_d3d11.h",
+    "CL/cl_dx9_media_sharing.h",
+    "CL/cl_dx9_media_sharing_intel.h",
+    "CL/cl_egl.h",
+    "CL/cl_ext.h",
+    "CL/cl_ext_intel.h",
+    "CL/cl_gl.h",
+    "CL/cl_gl_ext.h",
+    "CL/cl_half.h",
+    "CL/cl_icd.h",
+    "CL/cl_layer.h",
+    "CL/cl_platform.h",
+    "CL/cl_va_api_media_sharing_intel.h",
+    "CL/cl_version.h",
+    "CL/opencl.h",
+  ]
+
+  public_configs = [ ":opencl_headers_config" ]
+}