cpumask: CONFIG_DISABLE_OBSOLETE_CPUMASK_FUNCTIONS

Impact: new debug CONFIG options

This helps find unconverted code.  It currently breaks compile horribly,
but we never wanted a flag day so that's expected.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/lib/Kconfig b/lib/Kconfig
index fc5f5ee..03c2c24 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -170,4 +170,8 @@
 	  them on the stack.  This is a bit more expensive, but avoids
 	  stack overflow.
 
+config DISABLE_OBSOLETE_CPUMASK_FUNCTIONS
+       bool "Disable obsolete cpumask functions" if DEBUG_PER_CPU_MAPS
+       depends on EXPERIMENTAL && BROKEN
+
 endmenu