Add Intel legalization for division and multiplication.

These operations need custom legalization in order to use Intel's div
and idiv instructions.

cranelift/filetests/wasm/i32-arith.cton

@@ -55,9 +55,29 @@ ebb0(v0: i32, v1: i32):
     return v2
 }
 
-; function %i32_div(i32, i32) -> i32
-; function %i32_rem_s(i32, i32) -> i32
-; function %i32_rem_u(i32, i32) -> i32
+function %i32_div_s(i32, i32) -> i32 {
+ebb0(v0: i32, v1: i32):
+    v2 = sdiv v0, v1
+    return v2
+}
+
+function %i32_div_u(i32, i32) -> i32 {
+ebb0(v0: i32, v1: i32):
+    v2 = udiv v0, v1
+    return v2
+}
+
+function %i32_rem_s(i32, i32) -> i32 {
+ebb0(v0: i32, v1: i32):
+    v2 = srem v0, v1
+    return v2
+}
+
+function %i32_rem_u(i32, i32) -> i32 {
+ebb0(v0: i32, v1: i32):
+    v2 = urem v0, v1
+    return v2
+}
 
 function %i32_and(i32, i32) -> i32 {
 ebb0(v0: i32, v1: i32):