community/cloud-utils: make -growpart subpackage depend on partx instead of util-linux

Partx was moved out of the main util-linux and into a subpackage therefore cloud-utils-growpart's dependency for util-linux needs to be changed to partx instead.

Also remove cloud-utils-growpart dependency on coreutils and add patch growpart to use a flock command-line option that is understood by both util-linux and busybox's flock command.