Fix global find to be limited

[verm]

In

https://github.com/FreeBSDFoundation/pkgbasify/blob/main/pkgbasify.lua#L369

There is a find /. This bit me as I have about 15 NFS mounts so it sat there scanning all of them until it finally quit:

stack traceback:
	[C]: in function 'assert'
	./pkgbasify.lua:396: in function 'capture'
	./pkgbasify.lua:369: in function 'merge_pkgsaves'
	./pkgbasify.lua:145: in function 'execute_conversion'
	./pkgbasify.lua:70: in function 'main'
	./pkgbasify.lua:422: in main chunk
	[C]: in ?

There was no way for me to remove the mounts or do anything as now my system is in a broken state as it wiped out several files in /etc/ for instance /etc/passwd was reset along with several other files. Luckily I had an emergency terminal open just in case and was able to repair.

[grahamperrin]

pkgbasify/pkgbasify.lua

Lines 368 to 369 in ee835d5

	function merge_pkgsaves(workdir)
	for ours in capture("find / -name '*.pkgsave'"):gmatch("[^\n]+") do