[PATCH] kbuild: no redundant srctree in tags file

Avoid cluttering the tags/TAGS generated file with $(srctree) in the paths
if this is not needed.

This has two advantages:

- Saving about 20M on the size of the resulting tags file (which are used
  currently to store the absolute path of the file names rather than the
  relative one) when KBUILD_OUTPUT is not set.

- Keeping the tags file valid when the directory is renamed.

No change is done for who does make tags O=..., if this is wanted (I would
find that incommodous and non-typical for a developer, but anyway I've not
ruined functionality in that case).
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Makefile

@@ -1145,20 +1145,30 @@ endif # KBUILD_EXTMOD
 # Generate tags for editors
 # ---------------------------------------------------------------------------
 
+#We want __srctree to totally vanish out when KBUILD_OUTPUT is not set
+#(which is the most common case IMHO) to avoid unneeded clutter in the big tags file.
+#Adding $(srctree) adds about 20M on i386 to the size of the output file!
+
+ifeq ($(KBUILD_OUTPUT),)
+__srctree =
+else
+__srctree = $(srctree)/
+endif
+
 define all-sources
-	( find $(srctree) $(RCS_FIND_IGNORE) \
+	( find $(__srctree) $(RCS_FIND_IGNORE) \
 	       \( -name include -o -name arch \) -prune -o \
 	       -name '*.[chS]' -print; \
-	  find $(srctree)/arch/$(ARCH) $(RCS_FIND_IGNORE) \
+	  find $(__srctree)arch/$(ARCH) $(RCS_FIND_IGNORE) \
 	       -name '*.[chS]' -print; \
-	  find $(srctree)/security/selinux/include $(RCS_FIND_IGNORE) \
+	  find $(__srctree)security/selinux/include $(RCS_FIND_IGNORE) \
 	       -name '*.[chS]' -print; \
-	  find $(srctree)/include $(RCS_FIND_IGNORE) \
+	  find $(__srctree)include $(RCS_FIND_IGNORE) \
 	       \( -name config -o -name 'asm-*' \) -prune \
 	       -o -name '*.[chS]' -print; \
-	  find $(srctree)/include/asm-$(ARCH) $(RCS_FIND_IGNORE) \
+	  find $(__srctree)include/asm-$(ARCH) $(RCS_FIND_IGNORE) \
 	       -name '*.[chS]' -print; \
-	  find $(srctree)/include/asm-generic $(RCS_FIND_IGNORE) \
+	  find $(__srctree)include/asm-generic $(RCS_FIND_IGNORE) \
 	       -name '*.[chS]' -print )
 endef