vl: Don't mismatch g_strsplit()/g_free()

vl: Don't mismatch g_strsplit()/g_free()

It's a mismatch between g_strsplit and g_free, it will cause a memory leak as follow:

[root@localhost]# ./aarch64-softmmu/qemu-system-aarch64 -accel help
Accelerators supported in QEMU binary:
tcg
kvm
=================================================================
==1207900==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 8 byte(s) in 2 object(s) allocated from:
    #0 0xfffd700231cb in __interceptor_malloc (/lib64/libasan.so.4+0xd31cb)
    #1 0xfffd6ec57163 in g_malloc (/lib64/libglib-2.0.so.0+0x57163)
    #2 0xfffd6ec724d7 in g_strndup (/lib64/libglib-2.0.so.0+0x724d7)
    #3 0xfffd6ec73d3f in g_strsplit (/lib64/libglib-2.0.so.0+0x73d3f)
    #4 0xaaab66be5077 in main /mnt/sdc/qemu-master/qemu-4.2.0-rc0/vl.c:3517
    #5 0xfffd6e140b9f in __libc_start_main (/lib64/libc.so.6+0x20b9f)
    #6 0xaaab66bf0f53  (./build/aarch64-softmmu/qemu-system-aarch64+0x8a0f53)

Direct leak of 2 byte(s) in 2 object(s) allocated from:
    #0 0xfffd700231cb in __interceptor_malloc (/lib64/libasan.so.4+0xd31cb)
    #1 0xfffd6ec57163 in g_malloc (/lib64/libglib-2.0.so.0+0x57163)
    #2 0xfffd6ec7243b in g_strdup (/lib64/libglib-2.0.so.0+0x7243b)
    #3 0xfffd6ec73e6f in g_strsplit (/lib64/libglib-2.0.so.0+0x73e6f)
    #4 0xaaab66be5077 in main /mnt/sdc/qemu-master/qemu-4.2.0-rc0/vl.c:3517
    #5 0xfffd6e140b9f in __libc_start_main (/lib64/libc.so.6+0x20b9f)
    #6 0xaaab66bf0f53  (./build/aarch64-softmmu/qemu-system-aarch64+0x8a0f53)

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
Message-Id: <20200110091710.53424-2-pannengyuan@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>