Apply a patch backported from Ragel's "ragel-6" branch that allows it to
reliably generate usable code on aarch64-linux where the C/C++ "char" type is
unsigned by default, fixing the build of Knot on this platform.
* gnu/packages/patches/ragel-char-signedness.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/ragel.scm (ragel)[arguments]: Add custom phase for AArch64 that
applies the patch.
[native-inputs]: Add "patch" and patch file on AArch64.
Signed-off-by: Ludovic Courtès <ludo@gnu.org>
