configure.in: Don't use the dc command unless it is required

Some systems don't have the 'dc' command installed, and this causes
configure to print a warning message unnecessarily for a standard
(non-WIP and non-pre) release of e2fsprogs.

It's easy enough to avoid this problem, so let's do it.

Addresses-Sourceforge-Bug: #1893024

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2 files changed