Try to enable atomics differently

Author: Kerollmops

lmdb-master-sys/build.rs

@@ -137,7 +137,7 @@ fn main() {
         // Enable atomics on Windows
         .flag_if_supported("/std:c11")
         // Explicitly enable C11 atomics support
-        .define("_ENABLE_C11_ATOMICS", "1");
+        .flag_if_supported("/experimental:c11atomics");
 
     if cfg!(feature = "posix-sem") {
         builder.define("MDB_USE_POSIX_SEM", None);