Init static compiled-in env when no metadata present.

With this, a static environment can be compiled in via config(5).  This allows,
among other things, the use of a compiled-in debug console (hw.uart.dbgport) for
kgdb.

sys/powerpc/powerpc/machdep.c

@@ -274,6 +274,7 @@ powerpc_init(vm_offset_t fdt, vm_offset_t toc, vm_offset_t ofentry, void *mdp)
 	} else {
 		bzero(__sbss_start, __sbss_end - __sbss_start);
 		bzero(__bss_start, _end - __bss_start);
+		init_static_kenv(NULL, 0);
 	}
 #ifdef BOOKE
 	tlb1_init();