Fix a mismatched free in zmc binary

Reported by valgrind:
```
==5117== Mismatched free() / delete / delete []
==5117==    at 0x67C9360: operator delete(void*) (vg_replace_malloc.c:507)
==5117==    by 0x4199FA: main (in /usr/bin/zmc)
==5117==  Address 0x1839f820 is 0 bytes inside a block of size 8 alloc'd
==5117==    at 0x67C88A0: operator new[](unsigned long) (vg_replace_malloc.c:389)
==5117==    by 0x419D17: main (in /usr/bin/zmc)
```