test: fix x86_64-macos failures

This is just a temporary fix - I would like to unify all of x86_64
tests across linux and macos OSes.

test/incremental/x86_64-linux/assert_function.16.zig

@@ -0,0 +1,11 @@
+const hello = "hello".*;
+pub fn main() void {
+    assert(hello[1] == 'e');
+}
+
+pub fn assert(ok: bool) void {
+    if (!ok) unreachable; // assertion failure
+}
+
+// run
+//