Move dict.c from e2fsck to lib/support

Move dict.c from e2fsck to lib/support

The quota code required that we included dict.o in libsupport.a, so we
might as well just move dict.c and dict.h to lib/support, and then
have e2fsck use the version of dict.c in libsupport.a.  This
simplifies the build system and eliminates having two identical copies
of dict.o floating around in the build tree.

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