e2fsck, resize2fs: fix a fp precision error that can lead to a seg fault

e2fsck, resize2fs: fix a fp precision error that can lead to a seg fault

Commit 641b66b fixed a floating point precision error which can result
in a search algorithm looping forever.  It can also result in an array
index being out of bounds and causing a segfault.  Here are two more
cases in e2fsck and resize2fs that need to be fixed.  I've just used
the same fix from the that commit.

Signed-off-by: Lachlan McIlroy <lmcilroy@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>