Port g_cond_new to use GSlice

Now that nothing inside of GLib is using g_cond_new(), we can implement
it using GSlice.  Since the implementations for POSIX and Windows are
now the same, move it to gthread.c.

glib/gthread-posix.c

@@ -223,29 +223,6 @@ g_cond_timedwait (GCond  *cond,
   return FALSE;
 }
 
-/* {{{1 new/free API */
-
-GCond *
-g_cond_new (void)
-{
-  GCond *cond;
-
-  /* malloc() is temporary until all libglib users are ported away */
-  cond = malloc (sizeof (GCond));
-  if G_UNLIKELY (cond == NULL)
-    g_thread_abort (errno, "malloc");
-  g_cond_init (cond);
-
-  return cond;
-}
-
-void
-g_cond_free (GCond *cond)
-{
-  g_cond_clear (cond);
-  free (cond);
-}
-
 /* {{{1 GPrivate */
 
 #include "glib.h"

glib/gthread-win32.c

@@ -252,28 +252,6 @@ g_cond_timed_wait (GCond    *cond,
     }
 }
 
-/* {{{1 new/free API */
-GCond *
-g_cond_new (void)
-{
-  GCond *cond;
-
-  /* malloc() is temporary until all libglib users are ported away */
-  cond = malloc (sizeof (GCond));
-  if G_UNLIKELY (cond == NULL)
-    g_thread_abort (errno, "malloc");
-  g_cond_init (cond);
-
-  return cond;
-}
-
-void
-g_cond_free (GCond *cond)
-{
-  g_cond_clear (cond);
-  free (cond);
-}
-
 /* {{{1 GPrivate */
 
 #include "glib.h"

glib/gthread.c

@@ -2591,3 +2591,21 @@ g_mutex_free (GMutex *mutex)
   g_mutex_clear (mutex);
   g_slice_free (GMutex, mutex);
 }
+
+GCond *
+g_cond_new (void)
+{
+  GCond *cond;
+
+  cond = g_slice_new (GCond);
+  g_cond_init (cond);
+
+  return cond;
+}
+
+void
+g_cond_free (GCond *cond)
+{
+  g_cond_clear (cond);
+  g_slice_free (GCond, cond);
+}