Added cl_khr_fp16 extension support for test_astype from basic (#1706)

* Added support for cl_khr_fp16 extenstion in test_astype from basic (issue #142, basic)

* Added correction to iterate over vector of types

* Fixed case with both fp16 and fp64 supported

* Cosmetic corrections due to code review

* Cosmetic corrections due to code review

test_conformance/basic/utils.h

@@ -0,0 +1,41 @@
+//
+// Copyright (c) 2023 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.
+//
+
+#ifndef BASIC_UTILS_H
+#define BASIC_UTILS_H
+
+#include <memory>
+#include <string>
+
+inline std::string concat_kernel(const char *sstr[], int num)
+{
+    std::string res;
+    for (int i = 0; i < num; i++) res += std::string(sstr[i]);
+    return res;
+}
+
+template <typename... Args>
+inline std::string str_sprintf(const std::string &str, Args... args)
+{
+    int str_size = std::snprintf(nullptr, 0, str.c_str(), args...) + 1;
+    if (str_size <= 0) throw std::runtime_error("Formatting error.");
+    size_t s = static_cast<size_t>(str_size);
+    std::unique_ptr<char[]> buffer(new char[s]);
+    std::snprintf(buffer.get(), s, str.c_str(), args...);
+    return std::string(buffer.get(), buffer.get() + s - 1);
+}
+
+#endif // BASIC_UTIL_H