mkisoimages.sh: remove obsolete x$var convention

Description

mkisoimages.sh: remove obsolete x$var convention

Ancient shells had trouble with empty variables but this has not been
relevant for FreeBSD for a very long time (decades?).

Details

Committed
emasteMon, Sep 4, 10:37 PM
Parents
rS323164: MFC r303188,r303190,r303271,r303438,r303453: Warn flags for gcc 6.1
Branches
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