target-alpha: Implement rs/rc properly.

This is a per-cpu flag; there's no need for a spinlock of any kind.

We were also failing to manipulate the flag with $31 as a target reg
and failing to clear the flag on execution of a return-from-interrupt
instruction.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
diff --git a/linux-user/main.c b/linux-user/main.c
index 71a1b67..5680d8e 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -2358,6 +2358,11 @@
     while (1) {
         trapnr = cpu_alpha_exec (env);
 
+        /* All of the traps imply a transition through PALcode, which
+           implies an REI instruction has been executed.  Which means
+           that the intr_flag should be cleared.  */
+        env->intr_flag = 0;
+
         switch (trapnr) {
         case EXCP_RESET:
             fprintf(stderr, "Reset requested. Exit\n");
@@ -2444,7 +2449,7 @@
                                     env->ir[IR_A0], env->ir[IR_A1],
                                     env->ir[IR_A2], env->ir[IR_A3],
                                     env->ir[IR_A4], env->ir[IR_A5]);
-		if (trapnr != TARGET_NR_sigreturn
+                if (trapnr != TARGET_NR_sigreturn
                     && trapnr != TARGET_NR_rt_sigreturn) {
                     env->ir[IR_V0] = (sysret < 0 ? -sysret : sysret);
                     env->ir[IR_A3] = (sysret < 0);