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)
    kata-containers#1 0xfffd6ec57163 in g_malloc (/lib64/libglib-2.0.so.0+0x57163)
    kata-containers#2 0xfffd6ec724d7 in g_strndup (/lib64/libglib-2.0.so.0+0x724d7)
    kata-containers#3 0xfffd6ec73d3f in g_strsplit (/lib64/libglib-2.0.so.0+0x73d3f)
    kata-containers#4 0xaaab66be5077 in main /mnt/sdc/qemu-master/qemu-4.2.0-rc0/vl.c:3517
    kata-containers#5 0xfffd6e140b9f in __libc_start_main (/lib64/libc.so.6+0x20b9f)
    kata-containers#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)
    kata-containers#1 0xfffd6ec57163 in g_malloc (/lib64/libglib-2.0.so.0+0x57163)
    kata-containers#2 0xfffd6ec7243b in g_strdup (/lib64/libglib-2.0.so.0+0x7243b)
    kata-containers#3 0xfffd6ec73e6f in g_strsplit (/lib64/libglib-2.0.so.0+0x73e6f)
    kata-containers#4 0xaaab66be5077 in main /mnt/sdc/qemu-master/qemu-4.2.0-rc0/vl.c:3517
    kata-containers#5 0xfffd6e140b9f in __libc_start_main (/lib64/libc.so.6+0x20b9f)
    kata-containers#6 0xaaab66bf0f53  (./build/aarch64-softmmu/qemu-system-aarch64+0x8a0f53)

Reported-by: Euler Robot <[email protected]>
Signed-off-by: Pan Nengyuan <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

vl.c

@@ -3501,7 +3501,7 @@ int main(int argc, char **argv, char **envp)
                             gchar **optname = g_strsplit(typename,
                                                          ACCEL_CLASS_SUFFIX, 0);
                             printf("%s\n", optname[0]);
-                            g_free(optname);
+                            g_strfreev(optname);
                         }
                         g_free(typename);
                     }