state_tracker: replace __FUNCTION__ with __func__

Consistently just use C99's __func__ everywhere.
The patch was verified with Microsoft Visual studio 2013
redistributable package(RTM version number: 18.0.21005.1)
Next MSVC versions intends to support __func__.
No functional changes.

Acked-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Marius Predut <marius.predut@intel.com>

src/mesa/state_tracker/st_program.c

@@ -403,7 +403,7 @@ st_translate_vertex_program(struct st_context *st,
    return vpv;
 
 fail:
-   debug_printf("%s: failed to translate Mesa program:\n", __FUNCTION__);
+   debug_printf("%s: failed to translate Mesa program:\n", __func__);
    _mesa_print_program(&stvp->Base.Base);
    debug_assert(0);