i386: kvmvapic: initialise imm32 variable

When processing Task Priorty Register(TPR) access, it could leak
automatic stack variable 'imm32' in patch_instruction().
Initialise the variable to avoid it.

Reported by: Donghai Zdh <donghai.zdh@alibaba-inc.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: NPrasad J Pandit <pjp@fedoraproject.org>
Message-Id: <1460013608-16670-1-git-send-email-ppandit@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

(cherry picked from commit 691a02e2)
Signed-off-by: NMichael Roth <mdroth@linux.vnet.ibm.com>

hw/i386/kvmvapic.c

@@ -394,7 +394,7 @@ static void patch_instruction(VAPICROMState *s, X86CPU *cpu, target_ulong ip)
     CPUX86State *env = &cpu->env;
     VAPICHandlers *handlers;
     uint8_t opcode[2];
-    uint32_t imm32;
+    uint32_t imm32 = 0;
     target_ulong current_pc = 0;
     target_ulong current_cs_base = 0;
     int current_flags = 0;