libsysprof-capture: Drop GLib dependency

None of the code uses it any more. This means that `libsysprof-capture.a`
can now be used within `libglib-2.0.so` for collecting main loop
statistics.

Brought to you by Opeth’s Deliverance on repeat.

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

Fixes: #40

src/libsysprof-capture/sysprof-capture-writer-cat.c

@@ -58,7 +58,6 @@
 
 #include <assert.h>
 #include <errno.h>
-#include <glib/gstdio.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdlib.h>