patch.bbclass: allow importing patches into other dirs

This is taken from openembedded.master:
commit 9d0d70da60ca8ef278916f442125d41161846f38
Author: Chris Larson <chris_larson@mentor.com>
Date:   Mon Aug 23 13:03:55 2010 -0400

    patch: allow importing patches into other dirs

    Use the 'patchdir' flag.  If relative, it's assumed to be relative to ${S}.
    It creates a patchset class per patch directory, so for quilt this results i
    multiple .pc/patches directories to manage each of the patchsets.

    (From OE-Core rev: 01e4609ee8441c8212725fd062782313caae0708)

Signed-off-by: Chris Larson <chris_larson@mentor.com>

Signed-off-by: Tom Rini <tom_rini@mentor.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/patch.bbclass

@@ -31,10 +31,8 @@ python patch_do_patch() {
 
 	path = os.getenv('PATH')
 	os.putenv('PATH', bb.data.getVar('PATH', d, 1))
-	patchset = cls(s, d)
-	patchset.Clean()
 
-	resolver = rcls(patchset)
+	classes = {}
 
 	workdir = bb.data.getVar('WORKDIR', d, 1)
 	for url in src_uri:
@@ -117,6 +115,21 @@ python patch_do_patch() {
 				bb.note("Patch '%s' doesn't apply to revision" % pname)
 				continue
 
+		if "patchdir" in parm:
+			patchdir = parm["patchdir"]
+			if not os.path.isabs(patchdir):
+				patchdir = os.path.join(s, patchdir)
+		else:
+			patchdir = s
+
+		if not patchdir in classes:
+			patchset = cls(patchdir, d)
+			resolver = rcls(patchset)
+			classes[patchdir] = (patchset, resolver)
+			patchset.Clean()
+		else:
+			patchset, resolver = classes[patchdir]
+
 		bb.note("Applying patch '%s' (%s)" % (pname, oe.path.format_display(local, d)))
 		try:
 			patchset.Import({"file":local, "remote":url, "strippath": striplevel}, True)