sparc: Use g_memdup() instead of g_new0() + memcpy()

There is no need to make sure that the memory is zeroed after the
allocation if we also immediatly fill the whole buffer afterwards
with memcpy(). Thus g_new0 should be g_new instead. But since we
are also doing a memcpy() here, we can also simply replace both
with g_memdup() instead.

Backports commit a337f295defad7eb977da4d6317cf70f7f2fa4b4 from qemu

qemu/target-sparc/cpu.c

@@ -109,8 +109,7 @@ static int cpu_sparc_register(struct uc_struct *uc, SPARCCPU *cpu, const char *c
         return -1;
     }
 
-    env->def = g_new0(sparc_def_t, 1);
-    memcpy(env->def, def, sizeof(*def));
+    env->def = g_memdup(def, sizeof(*def));
 
     featurestr = strtok(NULL, ",");
     sparc_cpu_parse_features(CPU(cpu), featurestr, &err);