kbuild: move tags from ARCH and include/ ahead of drivers

Move tags extracted from the ARCH and include/ sub-trees ahead of
those from device drivers, so that the former will appear first
during searches.

Saves user time during interactive searches for certain patterns
that happen to find unwanted matches in driver files.

Example in emacs:
	 "M-x find-tag PAGE_SIZE"
	 "M-1 M-." (repeated until definition from asm-i386/page.h appears)
Signed-off-by: Don Mullis <dwm@meer.net>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Makefile

@@ -1278,10 +1278,7 @@ endif
 ALLSOURCE_ARCHS := $(ARCH)
 
 define find-sources
-        ( find $(__srctree) $(RCS_FIND_IGNORE) \
-	       \( -name include -o -name arch \) -prune -o \
-	       -name $1 -print; \
-	  for ARCH in $(ALLSOURCE_ARCHS) ; do \
+        ( for ARCH in $(ALLSOURCE_ARCHS) ; do \
 	       find $(__srctree)arch/$${ARCH} $(RCS_FIND_IGNORE) \
 	            -name $1 -print; \
 	  done ; \
@@ -1295,7 +1292,11 @@ define find-sources
 	            -name $1 -print; \
 	  done ; \
 	  find $(__srctree)include/asm-generic $(RCS_FIND_IGNORE) \
-	       -name $1 -print )
+	       -name $1 -print; \
+	  find $(__srctree) $(RCS_FIND_IGNORE) \
+	       \( -name include -o -name arch \) -prune -o \
+	       -name $1 -print; \
+	  )
 endef
 
 define all-sources