[PATCH] uml: Remove build dependency on perl

To quote .config into config.c for building the result into the code, use sed
instead of perl, as requested by one "embedded" UML user (which notes that
perl is a big requirement, while busybox provides sed which is used in this
patch).

I've tested that there are only cosmethical differences in the produced
config.c file, which don't change at all the result (i.e.  "a" is replaced by
"" "a" at the beginning, which is non-significant).

Reported by, and initial patch provided by, Rob Landley.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/kernel/Makefile

@@ -4,7 +4,7 @@
 #
 
 extra-y := vmlinux.lds
-clean-files := vmlinux.lds.S
+clean-files := vmlinux.lds.S config.tmp
 
 obj-y = checksum.o config.o exec_kern.o exitcode.o \
 	helper.o init_task.o irq.o irq_user.o ksyms.o main.o mem.o mem_user.o \
@@ -34,11 +34,25 @@ CFLAGS_frame.o := -fno-omit-frame-pointer
 $(USER_OBJS) : %.o: %.c
 	$(CC) $(USER_CFLAGS) $(CFLAGS_$(notdir $@)) -c -o $@ $<
 
-QUOTE = 'my $$config=`cat $(TOPDIR)/.config`; $$config =~ s/"/\\"/g ; $$config =~ s/\n/\\n"\n"/g ; while(<STDIN>) { $$_ =~ s/CONFIG/$$config/; print $$_ }'
+targets += config.c
 
-quiet_cmd_quote = QUOTE   $@
-cmd_quote = $(PERL) -e $(QUOTE) < $< > $@
+# Be careful with the below Sed code - sed is pitfall-rich!
+# We use sed to lower build requirements, for "embedded" builders for instance.
 
-targets += config.c
-$(obj)/config.c : $(src)/config.c.in $(TOPDIR)/.config FORCE
-	$(call if_changed,quote)
+$(obj)/config.tmp: $(objtree)/.config FORCE
+	$(call if_changed,quote1)
+
+quiet_cmd_quote1 = QUOTE   $@
+      cmd_quote1 = sed -e 's/"/\\"/g' -e 's/^/"/' -e 's/$$/\\n"/' \
+		   $< > $@
+
+$(obj)/config.c: $(src)/config.c.in $(obj)/config.tmp FORCE
+	$(call if_changed,quote2)
+
+quiet_cmd_quote2 = QUOTE   $@
+      cmd_quote2 = sed -e '/CONFIG/{'          \
+		  -e 's/"CONFIG"\;/""/'        \
+		  -e 'r $(obj)/config.tmp'     \
+		  -e 'a""\;'                   \
+		  -e '}'                       \
+		  $< > $@