Try using C for the wasm test platform

compiler/test_gen/src/helpers/wasm.rs

@@ -122,7 +122,7 @@ pub fn helper_wasm<'a, T: Wasm32TestResult>(
     );
 
     // We can either generate the test platform or write an external source file, whatever works
-    generate_test_platform(&mut wasm_module, arena);
+    // generate_test_platform(&mut wasm_module, arena);
 
     let mut module_bytes = std::vec::Vec::with_capacity(4096);
     wasm_module.serialize_mut(&mut module_bytes);

compiler/test_gen/src/helpers/wasm_test_platform.c

@@ -0,0 +1,23 @@
+#include <stdlib.h>
+extern void* test_wrapper();
+
+void* roc_alloc(size_t size, unsigned int alignment) {
+    return malloc(size);
+}
+
+void* roc_realloc(void* ptr, size_t old_size, size_t new_size, unsigned int alignment) {
+  return realloc(ptr, new_size);
+}
+
+void roc_dealloc(void* ptr, unsigned int alignment) {
+    free(ptr);
+}
+
+// Having a main function seems to make it easier to convince tools
+// to include everything in the output binary.
+// Using C as the source language makes it easier to convince them
+// to include libc for wasm target, not host.
+// The returned int is the memory address of the test result
+int main(void) {
+    return test_wrapper();
+}