wasm: Add support for passive data and element segments (#1389)

This is part of the bulk memory and reference types proposals.

cranelift/wasmtests/passive-data.wat

@@ -0,0 +1,11 @@
+(module
+  (data $passive "this is a passive data segment")
+
+  (func (export "init") (param i32 i32 i32)
+    local.get 0 ;; dst
+    local.get 1 ;; src
+    local.get 2 ;; cnt
+    memory.init $passive)
+
+  (func (export "drop")
+    data.drop $passive))

cranelift/wasmtests/table-copy.wat

@@ -0,0 +1,22 @@
+(module $n
+  (table $t (import "m" "t") 6 funcref)
+
+  (func $i (param i32 i32 i32 i32 i32 i32) (result i32) (local.get 3))
+  (func $j (param i32 i32 i32 i32 i32 i32) (result i32) (local.get 4))
+  (func $k (param i32 i32 i32 i32 i32 i32) (result i32) (local.get 5))
+
+  (table $u (export "u") funcref (elem $i $j $k $i $j $k))
+
+  (func (export "copy_to_t_from_u") (param i32 i32 i32 i32) (result i32)
+    local.get 0
+    local.get 1
+    local.get 2
+    local.get 3
+    table.copy $t $u)
+
+  (func (export "copy_to_u_from_t") (param i32 i32 i32 i32) (result i32)
+    local.get 0
+    local.get 1
+    local.get 2
+    local.get 3
+    table.copy $u $t))