hooks/strip: before stripping make sure files have write bit set.

... otherwise strip(1) errors out. Perl installs shlibs without write
bit set and results in EPERM errors.

Perl could be fixed instead, but meanwhile this works.

common/hooks/post-install/03-strip-and-debug-pkgs.sh

@@ -81,6 +81,7 @@ hook() {
 		fi
 		case "$(file -bi "$f")" in
 		application/x-executable*)
+			chmod +w "$f"
 			if echo "$(file $f)" | grep -q "statically linked"; then
 				# static binary
 				$STRIP "$f"
@@ -101,6 +102,7 @@ hook() {
 			fi
 			;;
 		application/x-sharedlib*)
+			chmod +w "$f"
 			# shared library
 			make_debug "$f"
 			$STRIP --strip-unneeded "$f"
@@ -120,6 +122,7 @@ hook() {
 			attach_debug "$f"
 			;;
 		application/x-archive*)
+			chmod +w "$f"
 			$STRIP --strip-debug "$f"
 			if [ $? -ne 0 ]; then
 				msg_red "$pkgver: failed to strip ${f#$PKGDESTDIR}\n"