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.c

@@ -64,7 +64,6 @@
 #include <endian.h>
 #include <errno.h>
 #include <fcntl.h>
-#include <glib/gstdio.h>
 #include <limits.h>
 #include <stdlib.h>
 #include <string.h>