linux-kbuild: Update genksyms makefile to run flex and bison

The C code generated by these tools used to be included in the source
tree but has now been removed.

debian/changelog

@@ -11,6 +11,7 @@ linux (4.17~rc1-1~exp1) UNRELEASED; urgency=medium
   * Documentation: typec.rst: Use literal-block element with ascii art
   * Documentation: Update references to drivers/base/firmware_class.c
   * [armhf] Enable MTD_NAND_MARVELL as module, replacing MTD_NAND_PXA3xx
+  * linux-kbuild: Update genksyms makefile to run flex and bison
 
  -- Ben Hutchings <ben@decadent.org.uk>  Thu, 19 Apr 2018 21:37:24 +0100
 

debian/rules.d/scripts/genksyms/Makefile

@@ -6,8 +6,11 @@ genksyms: genksyms.o parse.tab.o lex.lex.o
 
 lex.lex.o: keywords.c parse.tab.h
 
-%.c: %.c_shipped
-	ln -s $< $@
+parse.tab.c: parse.y
+	$(YACC) -o$@ -t -l $<
 
-%.h: %.h_shipped
-	ln -s $< $@
+parse.tab.h: parse.y
+	$(YACC) -o/dev/null --defines=$@ -t -l $<
+
+lex.lex.c: lex.l
+	$(LEX) -o$@ -L $<

debian/templates/control.source.in

@@ -28,7 +28,7 @@ Build-Depends-Arch:
 # used by upstream to build perf documentation
  asciidoc-base <!stage1 !nodoc !pkg.linux.notools>,
  xmlto <!stage1 !nodoc !pkg.linux.notools>,
-# used by upstream to build kconfig and perf
+# used by upstream to build genksyms, kconfig, and perf
  bison <!stage1>,
 # - flex needs to run on the host; we have the same problem as for openssl
  flex (>= 2.6.1-1.1~) <!stage1>,