This patch rebases flex to upstream version 2.6.4 and thus drops all
backported upstream patches that the package has been carrying so far.
One exception is flex-2.6.0-yyless.patch which has no equivalent upstream.
I could not track the origin of this patch because flex development moved
from SourceForge to GitHub and in the process, sourceforge bug tracker
content has been lost. However, RHBZ #1281976 seems to suggest that this
patch was included in order to fix a libreswan build failure caused by a
flex integer comparison type mismatch bug. I dropped flex-2.6.0-yyless.patch
and confirmed that the Fedora libreswan package corresponding to
libreswan-3.25 builds successfully despite this patch being dropped.
Additionally, flex-2.6.4 FTBFS because it uses reallocarray but does not
define _GNU_SOURCE leading to a missing prototype for reallocarray. This
commit also includes the upstream patch that fixes this. The patch modifies
configure.ac, which necessitates executing autoreconf at build time and thus
a corresponding set of new build dependencies.
This is not a functional change and merely adds quilt scripts and a README
explaining their usage. In addition, it rewrites patch levels to be in line
with the result of 'quilt refresh -p ab'. No source changes are involved and
the source files are identical.
