- Use g_thread_new instead of g_thread create
- Drop explicit call of g_thread_init, it is done implicitely by GLib
since 2.32
- Since this bumps the minimum required GLib version add and extend the
pkg-config based version checks to error out on older GLib versions
The remaining codebase uses g_strdup() already so do the same for the
chime command too. This fixes a gcc warning caused by a missing include
for strdup().