x86_64: enable advanced test runner on Linux

lib/test_runner.zig

@@ -13,7 +13,7 @@ var fba = std.heap.FixedBufferAllocator.init(&cmdline_buffer);
 
 pub fn main() void {
     if (builtin.zig_backend == .stage2_wasm or
-        builtin.zig_backend == .stage2_x86_64 or
+        (builtin.zig_backend == .stage2_x86_64 and builtin.os.tag != .linux) or
         builtin.zig_backend == .stage2_aarch64)
     {
         return mainSimple() catch @panic("test failure");