libsysprof-capture: Use stdbool instead of gboolean

Another step towards dropping GLib as a dependency of
libsysprof-capture.

Unlike the previous commit which replaced GLib integer types with the
bitwise equivalent C standard types, `stdbool` is potentially a different
width from `gboolean`, so this is an ABI break.

It therefore involves some changes to callback functions in the tests
and tools, and in libsysprof.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Helps: #40

src/libsysprof-capture/sysprof-clock.c

@@ -58,6 +58,8 @@
 
 #include "config.h"
 
+#include <stdbool.h>
+
 #include "sysprof-clock.h"
 
 int sysprof_clock = -1;