Add tests for assert headers linkage specifications

Author: lbushi25

sycl/test/basic_tests/assert_header_with_c_linkage.cpp

@@ -0,0 +1,14 @@
+// RUN: %clangxx -fsycl -c %s
+
+// Verify that compilation works when assert.h is wrapped by a C linkage 
+// specification. 
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <assert.h>
+
+#ifdef __cplusplus
+}
+#endif

sycl/test/basic_tests/cassert_header_with_c_linkage.cpp

@@ -0,0 +1,14 @@
+// RUN: %clangxx -fsycl -c %s
+
+// Verify that compilation works when cassert is wrapped by a C linkage
+// specification.
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <cassert>
+
+#ifdef __cplusplus
+}
+#endif