Convert the wast test harness into a crate.

This uses a build.rs file to collect all the wast tests and create
individual `#[test]` lines for them, so that `cargo test` can run them
in parallel.

lib/wast/misc_testsuite/misc_traps.wast

@@ -0,0 +1,67 @@
+(module
+  (memory 1 1)
+  (func (export "load_oob")
+    i32.const 65536
+    i32.load
+    drop
+  )
+)
+
+(assert_trap (invoke "load_oob") "out of bounds memory access")
+(assert_trap (invoke "load_oob") "out of bounds memory access")
+
+(module
+  (memory 1 1)
+  (func (export "store_oob")
+    i32.const 65536
+    i32.const 65536
+    i32.store
+  )
+)
+
+(assert_trap (invoke "store_oob") "out of bounds memory access")
+(assert_trap (invoke "store_oob") "out of bounds memory access")
+
+(module
+  (memory 0 0)
+  (func (export "load_oob_0")
+    i32.const 0
+    i32.load
+    drop
+  )
+)
+
+(assert_trap (invoke "load_oob_0") "out of bounds memory access")
+(assert_trap (invoke "load_oob_0") "out of bounds memory access")
+
+(module
+  (memory 0 0)
+  (func (export "store_oob_0")
+    i32.const 0
+    i32.const 0
+    i32.store
+  )
+)
+
+(assert_trap (invoke "store_oob_0") "out of bounds memory access")
+(assert_trap (invoke "store_oob_0") "out of bounds memory access")
+
+(module
+  (func (export "divbyzero") (result i32)
+    i32.const 1
+    i32.const 0
+    i32.div_s
+  )
+)
+
+(assert_trap (invoke "divbyzero") "integer divide by zero")
+(assert_trap (invoke "divbyzero") "integer divide by zero")
+
+(module
+  (func (export "unreachable")
+    (unreachable)
+  )
+)
+
+(assert_trap (invoke "unreachable") "unreachable")
+(assert_trap (invoke "unreachable") "unreachable")

lib/wast/misc_testsuite/stack_overflow.wast

@@ -0,0 +1,26 @@
+(module
+  (func $foo
+    (call $foo)
+  )
+  (func (export "stack_overflow")
+    (call $foo)
+  )
+)
+
+(assert_exhaustion (invoke "stack_overflow") "call stack exhausted")
+(assert_exhaustion (invoke "stack_overflow") "call stack exhausted")
+
+(module
+  (func $foo
+    (call $bar)
+  )
+  (func $bar
+    (call $foo)
+  )
+  (func (export "stack_overflow")
+    (call $foo)
+  )
+)
+
+(assert_exhaustion (invoke "stack_overflow") "call stack exhausted")
+(assert_exhaustion (invoke "stack_overflow") "call stack exhausted")