__wasm_call_ctors is also emitted into C programs, and not optimized out in C++ programs if there are no ctors to call.

STR:

```
emcc tests\minimal_hello.c -o a.html -s MINIMAL_RUNTIME=1 -s ENVIRONMENT=web -s SUPPORT_ERRNO=0 -s MINIFY_HTML=0 -s TEXTDECODER=2 -O3 -g1 --closure 1 --profiling-funcs
```

Will generate

```wast
(module
(type $none_=>_none (func))
(type $i32_=>_none (func (param i32)))
(type $i32_i32_=>_i32 (func (param i32 i32) (result i32)))
(import "a" "a" (memory $1 256 256))
(data (i32.const 1024) "(char* str)<::>{ console.log(UTF8ToString(str)); }\00minimal hello!")
(import "a" "b" (func $console_log (param i32)))
(table $0 1 1 funcref)
(export "c" (table $0))
(export "d" (func $__wasm_call_ctors))
(export "e" (func $main))
(func $main (; 1 ;) (param $0 i32) (param $1 i32) (result i32)
(call $console_log
(i32.const 1075)
)
(i32.const 0)
)
(func $__wasm_call_ctors (; 2 ;)
(nop)
)
)
```
and
```js
var c;
c || (c = Module);
var d = new TextDecoder("utf8");
function e(a) {
if (!a) {
return "";
}
for (var k = a + NaN, b = a; !(b >= k) && f[b];) {
++b;
}
return d.decode(f.subarray(a, b));
}
var g = new WebAssembly.Memory({initial:256, maximum:256}), f = new Uint8Array(g.buffer), h;
WebAssembly.instantiate(c.wasm, {a:{b:function(a) {
console.log(e(a));
}, a:g}}).then(function(a) {
a = a.instance.exports;
h = a.e;
a.d();
h();
});
```
There is a call to `a.d();` in the generated JS file at it comes from the preamble without understanding of the number of wasm ctors, but that is a no-op, so could be optimized away.

This is a regression compared to fastcomp btw, there we dynamically emitted the ctor invocations (or grouped them into one call), which ended up not emitting a dummy function if there were no ctors.

Also the program is a C program, so there should not be any ctors to begin with? It would be nice for this to optimize out automatically.