bitbake: bitbake: command: Move split_mc_pn to runqueue

All of the other multiconfig splitting functions are located in runqueue
so move the function to split a pn/fn there also so that its easier to
see them all together. Fixes a case where the findBestProvider() command
wasn't working for multiconfig because it was looking for a prefix of
"multiconfig:" instead of the newer "mc:"

(Bitbake rev: 325827af66434affc2da460cc8b9a5c460e38056)

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/runqueue.py

@@ -46,6 +46,12 @@ def split_tid(tid):
     (mc, fn, taskname, _) = split_tid_mcfn(tid)
     return (mc, fn, taskname)
 
+def split_mc(n):
+    if n.startswith("mc:"):
+        _, mc, n = n.split(":", 2)
+        return (mc, n)
+    return ('', n)
+
 def split_tid_mcfn(tid):
     if tid.startswith('mc:'):
         elems = tid.split(':')