olsrd: fix compilation with bison version 3.7.1

Recent bison versions changed the way the parser output is generated,
which causes compilation of the generated oparse.c to fail with

[CC] src/cfgparser/oparse.c
src/cfgparser/oparse.c:265:10: fatal error: oparse.h-tmp: No such file
or directory
 #include "oparse.h-tmp"
          ^~~~~~~~~~~~~~

Fix the issue by generating the expected output files directly and by
modifying the *.c file in-place.

Suggested-by: Jo-Philipp Wich <jo@mein.io>
Signed-off-by: Nick Hainke <vincent@systemli.org>

olsrd/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=olsrd
 PKG_SOURCE_DATE:=2020-06-18
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL:=https://github.com/OLSR/olsrd.git

olsrd/patches/100-bison.patch

@@ -0,0 +1,20 @@
+diff --git a/src/cfgparser/local.mk b/src/cfgparser/local.mk
+index e767abfc..56e594e4 100644
+--- a/src/cfgparser/local.mk
++++ b/src/cfgparser/local.mk
+@@ -74,12 +74,8 @@ $(C)oparse.c: $(C)oparse.y $(C)olsrd_conf.h $(C)Makefile
+ ifeq ($(VERBOSE),0)
+ 	@echo "[BISON] $@"
+ endif
+-	$(MAKECMDPREFIX)$(BISON) -d -o "$@-tmp" "$<"
+-	$(MAKECMDPREFIX)sed	-e 's/register //' \
+-		-e '/^#line/s/$(call quote,$@-tmp)/$(call quote,$@)/' \
+-		< "$@-tmp" >"$@"
+-	$(MAKECMDPREFIX)mv "$(subst .c,.h,$@-tmp)" "$(subst .c,.h,$@)"
+-	$(MAKECMDPREFIX)$(RM) "$@-tmp" "$(subst .c,.h,$@-tmp)"
++	$(MAKECMDPREFIX)$(BISON) -d -o "$@" "$<"
++	$(MAKECMDPREFIX)sed -e 's/register //' "$@" > "$@.o" && mv "$@.o" "$@"
+ 
+ $(C)oparse.o: CFLAGS := $(filter-out -Wunreachable-code,$(CFLAGS))
+ 
+