ARM: Fix excess stack growth in interpreter.

src/vm_arm.dasc

@@ -335,7 +335,7 @@ static void build_subroutines(BuildCtx *ctx)
   |  // - The GC shrinks the stack in between.
   |  // - A return back from a lua_call() with (high) nresults adjustment.
   |  str BASE, L->top			// Save current top held in BASE (yes).
-  |  mov CARG2, KBASE
+  |  lsr CARG2, KBASE, #3
   |  mov CARG1, L
   |  bl extern lj_state_growstack	// (lua_State *L, int n)
   |  ldr BASE, L->top			// Need the (realloced) L->top in BASE.
@@ -389,7 +389,7 @@ static void build_subroutines(BuildCtx *ctx)
   |  str BASE, L->base
   |   add PC, PC, #4			// Must point after first instruction.
   |  str RC, L->top
-  |   lsr CARG3, RA, #3
+  |   lsr CARG2, RA, #3
   |2:
   |  // L->base = new base, L->top = top
   |  str PC, SAVE_PC