[libsecret] build: Add redirect Makefile for when $srcdir != $builddir

[Stefan Walter <stefw src gnome org>]

commit a3a6f5c9d842bc7a6c578bccd277368fd21faf96
Author: Stef Walter <stefw redhat com>
Date:   Sat Feb 13 12:27:18 2016 +0100

    build: Add redirect Makefile for when $srcdir != $builddir

 autogen.sh              |    8 +++++++-
 build/Makefile.redirect |    9 +++++++++
 2 files changed, 16 insertions(+), 1 deletions(-)
---
diff --git a/autogen.sh b/autogen.sh
index 8a2a1f2..75857de 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -104,6 +104,12 @@ cd $ORIGDIR || exit $?
 if test -z "$NOCONFIGURE"; then
         $srcdir/configure --enable-maintainer-mode $AUTOGEN_CONFIGURE_ARGS "$@" || exit $?
 
-        echo 
+       # Put a redirect makefile here
+       if [ ! -f $srcdir/Makefile ]; then
+           cat $srcdir/build/Makefile.redirect > $srcdir/Makefile
+           printf "\nREDIRECT = %s\n" "$(realpath $ORIGDIR)" >> $srcdir/Makefile
+       fi
+
+        echo
         echo "Now type 'make' to compile $PROJECT."
 fi
diff --git a/build/Makefile.redirect b/build/Makefile.redirect
new file mode 100644
index 0000000..db371eb
--- /dev/null
+++ b/build/Makefile.redirect
@@ -0,0 +1,9 @@
+# This redirects all make targets to builddir
+all:
+       $(MAKE) -C $(REDIRECT) all
+%:
+       $(MAKE) -C $(REDIRECT) $@
+ifeq ($(MAKEFLAGS), )
+JOBARG = -j4
+endif
+# REDIRECT=build