e2fsprogs: pass LDCONFIG=true also at install time

e2fsprogs: pass LDCONFIG=true also at install time

We correctly set LDCONFIG=true for MAKE_OPTS, but not for the other
steps which don't inherit it, and therefore e2fsprogs tries to use the
host ldconfig during staging and target installation, which causes some
weird error messages at build time (even if they don't abort the build).

Fix that by passing LDCONFIG=true at install time.

Signed-off-by: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>