Closes #585

Adds `#include <stdbool.h>` conditionally for C compilers.

Then the cython generate C source file can be compiled using gcc 9.3
as follows:

```
gcc -fmax-errors=1 a.c -fPIC -I$(python -c "import dpctl; print(dpctl.get_include())") -I$(python3-config --includes) $(pyt
hon3-config --ldflags) -fno-lto -shared -oa$(python3-config --extension-suffix)
```

Author: oleksandr-pavlyk

dpctl-capi/include/dpctl_data_types.h

@@ -37,6 +37,10 @@
 #include <inttypes.h>
 #include <stdint.h>
 
+#ifndef __cplusplus
+#include <stdbool.h>
+#endif
+
 #ifndef _MSC_VER
 
 #if !defined(UINT32_MAX)