libsysprof-capture: Use C11 types instead of GLib types

This is an almost entirely mechanical* conversion from (for example)
`gint` → `int`, `guint8` → `uint8_t`, etc.

It is not entirely complete, as many GLib functions are still used in
libsysprof-capture, which necessitate some use of GLib types.

It also avoids renaming `gboolean` → `bool` as that’s a slightly more
controversial change which will happen in the following commit.

*Code was manually realigned afterwards.

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

Helps: #40

src/libsysprof-capture/sysprof-capture-util.c

@@ -157,7 +157,7 @@ ssize_t
 #endif
 }
 
-gint32
+int32_t
 (_sysprof_getpid) (void)
 {
 #ifdef G_OS_WIN32