MIPS: Switch to dual-number mode. Fix soft-float interpreter.

src/lj_vm.h

@@ -66,6 +66,9 @@ LJ_ASMF double lj_vm_log2(double);
 #else
 #define lj_vm_log2	log2
 #endif
+#if !(defined(_LJ_DISPATCH_H) && LJ_TARGET_MIPS)
+LJ_ASMF int32_t LJ_FASTCALL lj_vm_modi(int32_t, int32_t);
+#endif
 
 #if LJ_HASJIT
 #if LJ_TARGET_X86ORX64
@@ -90,7 +93,6 @@ LJ_ASMF double lj_vm_exp2(double);
 #else
 #define lj_vm_exp2	exp2
 #endif
-LJ_ASMF int32_t LJ_FASTCALL lj_vm_modi(int32_t, int32_t);
 #if LJ_HASFFI
 LJ_ASMF int lj_vm_errno(void);
 #endif