target-xtensa: implement disas_xtensa_insn

Set up disas_xtensa_insn switch structure, mark required options on high
level groups. Implement arithmetic/bit logic/jump/call0.

Implement code generation loop with single step/breakpoint checking.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/target-xtensa/helpers.h b/target-xtensa/helpers.h
new file mode 100644
index 0000000..c298d74
--- /dev/null
+++ b/target-xtensa/helpers.h
@@ -0,0 +1,5 @@
+#include "def-helper.h"
+
+DEF_HELPER_1(exception, void, i32)
+
+#include "def-helper.h"