configure: support dash
configure: support dash

Dash doesn't support bash's substring notation (${val:a:b}), so switch
to cut and be thankful it isn't performance sensitive code.

Signed-off-by: Evan Nemerson <178b62e73cc3fab9e30bf27b2372c9ff92401915@nemerson.com>

jibsen/squash,jibsen/squash,Cloudef/squash,wolut/squash,quixdb/squash,wolut/squash,quixdb/squash,Cloudef/squash,jibsen/squash,quixdb/squash,wolut/squash,Cloudef/squash