sigreturn.c: split arch specific code into separate arch files
Split code that use arch-specific registers to separate arch files.
* sigreturn.c (sys_sigreturn): Move arch-specific code
to linux/*/arch_sigreturn.c, include "arch_sigreturn.c".
* linux/arch_sigreturn.c: New file.
* Makefile.am (EXTRA_DIST): Add linux/arch_sigreturn.c
and linux/*/arch_sigreturn.c files.
diff --git a/linux/arch_sigreturn.c b/linux/arch_sigreturn.c
new file mode 100644
index 0000000..80ec984
--- /dev/null
+++ b/linux/arch_sigreturn.c
@@ -0,0 +1 @@
+#warning sigreturn/rt_sigreturn signal mask decoding is not implemented for this architecture