groff: Fix determinism issue

Sometimes bison would regenerate source files and sometimes it would not
This is likely related to the patching of generated files by on of the
patches.

Drop those changes and force the files to regenerate in all cases since
we depend on bison-native anyway. This ensures the results are always
consistent.

(From OE-Core rev: 4449fa226e94f7124215c5ead43aadda7967f3af)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-extended/groff/groff_1.22.4.bb

@@ -18,6 +18,10 @@ SRC_URI = "${GNU_MIRROR}/groff/groff-${PV}.tar.gz \
 SRC_URI[md5sum] = "08fb04335e2f5e73f23ea4c3adbf0c5f"
 SRC_URI[sha256sum] = "e78e7b4cb7dec310849004fa88847c44701e8d133b5d4c13057d876c1bad0293"
 
+# Remove at the next upgrade
+PR = "r1"
+HASHEQUIV_HASH_VERSION .= ".1"
+
 DEPENDS = "bison-native"
 RDEPENDS_${PN} += "perl sed"
 
@@ -30,6 +34,13 @@ PARALLEL_MAKE = ""
 
 CACHED_CONFIGUREVARS += "ac_cv_path_PERL='/usr/bin/env perl' ac_cv_path_BASH_PROG='no' PAGE=A4"
 
+# Delete these generated files since we depend on bison-native
+# and regenerate them. Do it deterministically (always).
+do_configure_prepend() {
+	rm -f ${S}/src/preproc/eqn/eqn.cpp
+	rm -f ${S}/src/preproc/eqn/eqn.hpp
+}
+
 do_install_append() {
 	# Some distros have both /bin/perl and /usr/bin/perl, but we set perl location
 	# for target as /usr/bin/perl, so fix it to /usr/bin/perl.