generic compat_sys_rt_sigprocmask()

conditional on GENERIC_COMPAT_RT_SIGPROCMASK; by the end of that series
it will become the same thing as COMPAT and conditional will die out.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/Kconfig b/arch/Kconfig
index 6e4c32a..374a68a 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -359,6 +359,9 @@
 config GENERIC_SIGALTSTACK
 	bool
 
+config GENERIC_COMPAT_RT_SIGPROCMASK
+	bool
+
 #
 # ABI hall of shame
 #