sstate: Be consistent about sstate-inputdirs/outputdirs ending with '/'

The manifest file can become corrupted if sstate-inputdirs and sstate-outputdirs
don't have matching endings. This patch ensures that even if set incorrectly,
the code functions as intended, thereby handling manifest corruption safely.

(From OE-Core rev: 0109a3623a19f9ae289952a4f054e53c3eca4eaa)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/sstate.bbclass

@@ -111,6 +111,10 @@ def sstate_state_fromvars(d, task = None):
 
 def sstate_add(ss, source, dest, d):
     srcbase = os.path.basename(source)
+    if not source.endswith:
+         source = source + "/"
+    if not dest.endswith:
+         dest = dest + "/"
     ss['dirs'].append([srcbase, source, dest])
     return ss