irq: Introduce and use CPU_INTERRUPT_SSTEP_MASK.

This mask contains all of the bits that should be ignored while single
stepping in the debugger.  The mask contains 2 bits that are not currently
cleared, but are also never set.  The bits are included in the mask for
consistency in handling of the CPU_INTERRUPT_TGT_EXT_N bits.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/cpu-all.h b/cpu-all.h
index dd9c230..bc0dad8 100644
--- a/cpu-all.h
+++ b/cpu-all.h
@@ -837,6 +837,14 @@
 #define CPU_INTERRUPT_SIPI        CPU_INTERRUPT_TGT_INT_2
 #define CPU_INTERRUPT_MCE         CPU_INTERRUPT_TGT_EXT_4
 
+/* The set of all bits that should be masked when single-stepping.  */
+#define CPU_INTERRUPT_SSTEP_MASK \
+    (CPU_INTERRUPT_HARD          \
+     | CPU_INTERRUPT_TGT_EXT_0   \
+     | CPU_INTERRUPT_TGT_EXT_1   \
+     | CPU_INTERRUPT_TGT_EXT_2   \
+     | CPU_INTERRUPT_TGT_EXT_3   \
+     | CPU_INTERRUPT_TGT_EXT_4)
 
 #ifndef CONFIG_USER_ONLY
 typedef void (*CPUInterruptHandler)(CPUState *, int);