scripts/tags.sh: collect compiled source precisely

Parse compiled source from *.cmd but don't 'find' too many files that are
not related to compilation.

[[email protected]: don't expand symlinks by add option -s for realpath]
  Link: http://lkml.kernel.org/r/[email protected]

Signed-off-by: Jialu Xu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Joe Perches <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

scripts/tags.sh

@@ -91,20 +91,10 @@ all_sources()
 
 all_compiled_sources()
 {
-	for i in $(all_sources); do
-		case "$i" in
-			*.[cS])
-				j=${i/\.[cS]/\.o}
-				j="${j#$tree}"
-				if [ -e $j ]; then
-					echo $i
-				fi
-				;;
-			*)
-				echo $i
-				;;
-		esac
-	done
+	realpath -es $([ -z "$KBUILD_ABS_SRCTREE" ] && echo --relative-to=.) \
+		include/generated/autoconf.h $(find -name "*.cmd" -exec \
+		grep -Poh '(?(?=^source_.* \K).*|(?=^  \K\S).*(?= \\))' {} \+ |
+		awk '!a[$0]++') | sort -u
 }
 
 all_target_sources()