Add regression test for a spurious import

Author: athei

src/test/run-make/wasm-spurious-import/Makefile

@@ -0,0 +1,7 @@
+-include ../../run-make-fulldeps/tools.mk
+
+# only-wasm32-bare
+
+all:
+	$(RUSTC) main.rs -C overflow-checks=yes -C panic=abort -C lto -C opt-level=z --target wasm32-unknown-unknown
+	$(NODE) verify.js $(TMPDIR)/main.wasm

src/test/run-make/wasm-spurious-import/main.rs

@@ -0,0 +1,14 @@
+#![crate_type = "cdylib"]
+#![no_std]
+
+#[panic_handler]
+fn my_panic(_info: &core::panic::PanicInfo) -> ! {
+    loop {}
+}
+
+#[no_mangle]
+pub fn multer(a: i128, b: i128) -> i128 {
+    // Trigger usage of the __multi3 compiler intrinsic which then leads to an imported
+    // panic function in case of a bug. We verify that no imports exist in our verifier.
+    a * b
+}

src/test/run-make/wasm-spurious-import/verify.js

@@ -0,0 +1,9 @@
+const fs = require('fs');
+const process = require('process');
+const assert = require('assert');
+const buffer = fs.readFileSync(process.argv[2]);
+
+let m = new WebAssembly.Module(buffer);
+let imports = WebAssembly.Module.imports(m);
+console.log('imports', imports);
+assert.strictEqual(imports.length, 0);