added global add atomic intrinsic for CL

Author: Hugobros3

platforms/artic/intrinsics_opencl.impala

@@ -55,6 +55,7 @@
 #[import(cc = "device", name = "min")]               fn opencl_min(i32, i32) -> i32;
 #[import(cc = "device", name = "max")]               fn opencl_max(i32, i32) -> i32;
 #[import(cc = "device", name = "atomic_add")]        fn opencl_atomic_add_global(&mut addrspace(1)i32, i32) -> i32;
+#[import(cc = "device", name = "atomic_add")]        fn opencl_atomic_add_global_f32(&mut addrspace(1)f32, f32) -> f32;
 #[import(cc = "device", name = "atomic_add")]        fn opencl_atomic_add_shared(&mut addrspace(3)i32, i32) -> i32;
 #[import(cc = "device", name = "atomic_min")]        fn opencl_atomic_min_global(&mut addrspace(1)i32, i32) -> i32;
 #[import(cc = "device", name = "atomic_min")]        fn opencl_atomic_min_shared(&mut addrspace(3)i32, i32) -> i32;