wsutil/CMakeLists: add missing array.h
Fix array.h missing in debian packaging:
In file included from debian/headers-check.c:14:
debian/libwireshark-dev/usr/include/wireshark/epan/packet.h:15:10: fatal error: wsutil/array.h: No such file or directory
NOTE: I guess this would have been caught in CI if !7520 (merged) was reverted (not verified).