libgnt/libgnt

When someone uses our pc file they shouldn't need to explicitly add gobject to compile

Testing Done:
Ran configure and verified that `${builddir}/meson-private/gnt.pc` properly had `gobject-2.0` in `Required`

```
Requires: glib-2.0 >= 2.16.0, gobject-2.0
```

Reviewed at https://reviews.imfreedom.org/r/1478/
#include "gnt.h"
#include "gntfilesel.h"
static void
file_selected(GntFileSel *sel, const char *path, const char *filename)
{
g_printerr("%s %s\n", path, filename);
}
int main()
{
freopen(".error", "w", stderr);
fprintf(stdout, "\x1b]1;\x07\x1b]2;TEST\x07");
gnt_init();
GntWidget *w = gnt_file_sel_new();
gnt_file_sel_set_current_location(GNT_FILE_SEL(w), "/home/");
gnt_file_sel_set_dirs_only(GNT_FILE_SEL(w), TRUE);
gnt_file_sel_set_multi_select(GNT_FILE_SEL(w), TRUE);
gnt_widget_show(w);
g_signal_connect(G_OBJECT(w), "file_selected", G_CALLBACK(file_selected), NULL);
gnt_main();
gnt_quit();
return 0;
}