kbuild: fix make headers_install when path is too long

If headers_install is executed from a deep/long directory structure, the
shell's maximum argument length can be execeeded, which breaks the operation
with:

| make[2]: execvp: /bin/sh: Argument list too long
| make[2]: ***

Instead of passing each files name with the entire path, I give only the file
name without the source path and give this path as a new argument to
headers_install.pl.

Because there is three possible paths, I have tree input-files list, one per
path.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Tested-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/headers_install.sh

@@ -2,7 +2,7 @@
 
 if [ $# -lt 1 ]
 then
-	echo "Usage: headers_install.sh OUTDIR [FILES...]
+	echo "Usage: headers_install.sh OUTDIR SRCDIR [FILES...]
 	echo
 	echo "Prepares kernel header files for use by user space, by removing"
 	echo "all compiler.h definitions and #includes, removing any"
@@ -10,6 +10,7 @@ then
 	echo "asm/inline/volatile keywords."
 	echo
 	echo "OUTDIR: directory to write each userspace header FILE to."
+	echo "SRCDIR: source directory where files are picked."
 	echo "FILES:  list of header files to operate on."
 
 	exit 1
@@ -19,6 +20,8 @@ fi
 
 OUTDIR="$1"
 shift
+SRCDIR="$1"
+shift
 
 # Iterate through files listed on command line
 
@@ -34,7 +37,7 @@ do
 		-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 @' \
-		"$i" > "$OUTDIR/$FILE.sed" || exit 1
+		"$SRCDIR/$i" > "$OUTDIR/$FILE.sed" || exit 1
 	scripts/unifdef -U__KERNEL__ -D__EXPORTED_HEADERS__ "$OUTDIR/$FILE.sed" \
 		> "$OUTDIR/$FILE"
 	[ $? -gt 1 ] && exit 1