kbuild: Improve portability of some sed invocations

* Use BREs where EREs aren't necessary.
* Pass -E instead of -r to use EREs. This will be standardized in the
  next POSIX revision[0]. GNU sed supports this since 4.2 (May 2009),
  and busybox since 1.22.0 (Jan 2014).
* Use the [:space:] character class instead of ` \t` in bracket
  expressions. In bracket expressions, POSIX says that <backslash> loses
  its special meaning, so a conforming implementation cannot expand \t
  to <tab>[1].
* In BREs, use interval expressions (\{n,m\}) instead of non-standard
  features like \+ and \?.
* Use a loop instead of -s flag.

There are still plenty of other cases of non-standard sed invocations
(use of ERE features in BREs, in-place editing), but this fixes some
core ones.

[0] http://austingroupbugs.net/view.php?id=528
[1] http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_03_05

Signed-off-by: Michael Forney <forney@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

scripts/headers_install.sh

@@ -31,13 +31,13 @@ trap 'rm -f "$OUTDIR/$FILE" "$OUTDIR/$FILE.sed"' EXIT
 for i in "$@"
 do
 	FILE="$(basename "$i")"
-	sed -r \
-		-e 's/([ \t(])(__user|__force|__iomem)[ \t]/\1/g' \
-		-e 's/__attribute_const__([ \t]|$)/\1/g' \
+	sed -E \
+		-e 's/([[:space:](])(__user|__force|__iomem)[[:space:]]/\1/g' \
+		-e 's/__attribute_const__([[:space:]]|$)/\1/g' \
 		-e 's@^#include <linux/compiler(|_types).h>@@' \
 		-e 's/(^|[^a-zA-Z0-9])__packed([^a-zA-Z0-9_]|$)/\1__attribute__((packed))\2/g' \
-		-e 's/(^|[ \t(])(inline|asm|volatile)([ \t(]|$)/\1__\2__\3/g' \
-		-e 's@#(ifndef|define|endif[ \t]*/[*])[ \t]*_UAPI@#\1 @' \
+		-e 's/(^|[[:space:](])(inline|asm|volatile)([[:space:](]|$)/\1__\2__\3/g' \
+		-e 's@#(ifndef|define|endif[[:space:]]*/[*])[[:space:]]*_UAPI@#\1 @' \
 		"$SRCDIR/$i" > "$OUTDIR/$FILE.sed" || exit 1
 	scripts/unifdef -U__KERNEL__ -D__EXPORTED_HEADERS__ "$OUTDIR/$FILE.sed" \
 		> "$OUTDIR/$FILE"