Fix linker string comparison for dash
Fix linker string comparison for dash

Calling out to shell results in /bin/sh, so using a Bash-ism there won't
necesssarily work.  In particular, this breaks on Debian.

Suggested-by: Martin Haaß <0bcc71a06885df29d6584e5a7969eb3dd1cba680@gmail.com>
Resolves: #193
Signed-off-by: Robbie Harwood <3f8631879978f4cea53bf1163760f1ac18f9cb08@redhat.com>

rhboot/efivar,rhinstaller/efivar,rhboot/efivar,rhinstaller/efivar