grep fails in configure on BSD

[yurivict]

configure prints this and continues like this error didn't happen:

usage: grep [-abcDEFGHhIiLlmnOoPqRSsUVvwxz] [-A num] [-B num] [-C num]
	[-e pattern] [-f file] [--binary-files=value] [--color=when]
	[--context=num] [--directories=action] [--label] [--line-buffered]
	[--null] [pattern] [file ...]
cat: /sys/devices/system/cpu/cpu0/cache/index0/coherency_line_size: No such file or directory
usage: grep [-abcDEFGHhIiLlmnOoPqRSsUVvwxz] [-A num] [-B num] [-C num]
	[-e pattern] [-f file] [--binary-files=value] [--color=when]
	[--context=num] [--directories=action] [--label] [--line-buffered]
	[--null] [pattern] [file ...]
usage: grep [-abcDEFGHhIiLlmnOoPqRSsUVvwxz] [-A num] [-B num] [-C num]
	[-e pattern] [-f file] [--binary-files=value] [--color=when]
	[--context=num] [--directories=action] [--label] [--line-buffered]
	[--null] [pattern] [file ...]

FreeBSD 13.1

[shintaro-iwasaki]

Thanks for reporting the issues! The current configure.ac depends on GNU's grep.

Though this particular issue should not break the Argobots feature (i.e., the cache line detection mechanism should just choose the default one), it should be surely fixed. Please give us some time for this (and #376, which we are investigating too).