target-ppc: Introduce unrealizefn for PowerPCCPU

Use it to clean up the opcode table, resolving a former TODO from Jocelyn.
Also switch from malloc() to g_malloc().

Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index aa1d013..0ede077 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -886,6 +886,8 @@
 /* The whole PowerPC CPU context */
 #define NB_MMU_MODES 3
 
+#define PPC_CPU_OPCODES_LEN 0x40
+
 struct CPUPPCState {
     /* First are the most commonly used resources
      * during translated code execution
@@ -1039,7 +1041,7 @@
 
     /* Those resources are used only during code translation */
     /* opcode handlers */
-    opc_handler_t *opcodes[0x40];
+    opc_handler_t *opcodes[PPC_CPU_OPCODES_LEN];
 
     /* Those resources are used only in QEMU core */
     target_ulong hflags;      /* hflags is a MSR & HFLAGS_MASK         */