Fixed SYSENTER, SYSEXIT, SYSCALL, and SYSRET;

SYSCALL and SYSRET are now perfectly in line with AMD's specification;
Improvements to the API call to gracefully stop the emulator.

src/codegen_new/codegen_ops_mmx_loadstore.c

@@ -41,6 +41,9 @@ uint32_t ropMOVD_d_r(codeblock_t *block, ir_data_t *ir, uint8_t opcode, uint32_t
 {
         int src_reg = (fetchdat >> 3) & 7;
 
+        if (cpu_iscyrix && in_smm)
+                return 0;
+
         uop_MMX_ENTER(ir);
         codegen_mark_code_present(block, cs+op_pc, 1);
         if ((fetchdat & 0xc0) == 0xc0)