printf test cases for cl_khr_command_buffer extenstion (#1592)

* Added printf test case for cl_khr_command_buffer extenstion according to point 1.6 from:

https://github.com/KhronosGroup/OpenCL-CTS/issues/1369

* Corrections related to macos and windows build

* Added missing header

* Added corrections related to code review of draft PR:

https://github.com/KhronosGroup/OpenCL-CTS/pull/1592

refers to issue #1369, p.1.6:

https://github.com/KhronosGroup/OpenCL-CTS/issues/1369

* minor fix for previous commit

* printf capability condition moved to ::Skip method (#1369, p.1.6):

https://github.com/KhronosGroup/OpenCL-CTS/issues/1369

* Applied minor corrections related to code review (#1369, p.1.6):

https://github.com/KhronosGroup/OpenCL-CTS/issues/1369

* Added correction to replace string literals with sequence of characters printf arguments (issue #1369, printf)

* Added clang formatting.

* Added header related to android build (issue #1369, printf)

* Fixed memory leak

* Fixed memory leak in test_printf

* Added cosmetic fix for last commit

test_conformance/extensions/cl_khr_command_buffer/main.cpp

@@ -50,6 +50,8 @@ test_definition test_list[] = {
     ADD_TEST(copy_image_to_buffer),
     ADD_TEST(copy_buffer_rect),
     ADD_TEST(barrier_wait_list),
+    ADD_TEST(basic_printf),
+    ADD_TEST(simultaneous_printf),
     ADD_TEST(basic_set_kernel_arg),
     ADD_TEST(pending_set_kernel_arg),
     ADD_TEST(event_info_command_type),