adds SPIR-V tests for scalar printf operands (#2211)

Adds targeted SPIR-V tests for printf with scalar operands.  See:

* https://github.com/KhronosGroup/OpenCL-Docs/issues/1211
* https://github.com/KhronosGroup/OpenCL-Docs/pull/1236

The fp32 test is likely to be the most interesting, especially on
devices that support fp64, because printf with scalar fp32 operands is
not generated by default in this case with Clang and the SPIR-V LLVM
Translator.

test_common/harness/os_helpers.cpp

@@ -577,7 +577,7 @@ char* get_temp_filename()
     close(fd);
 #elif defined(_WIN32)
     UINT ret = GetTempFileName(".", "tmp", 0, gFileName);
-    if (ret == 0) return gFileName;
+    if (ret == 0) return strdup(gFileName);
 #else
     MTdata d = init_genrand((cl_uint)time(NULL));
     sprintf(gFileName, "tmpfile.%u", genrand_int32(d));