call_once fix, removed rx: OFF configs

src/carrot_crypto.cpp

@@ -9,7 +9,6 @@ extern "C" {
 }
 
 #include <cstring>
-#include <mutex>
 #include "log.h"
 
 LOG_CATEGORY(CarrotCrypto)
@@ -59,15 +58,14 @@ static const uint8_t identity_point[32] = {
 // Get mx25519 implementation (cached)
 static const mx25519_impl* get_mx25519_impl()
 {
-    static std::once_flag of;
-    static const mx25519_impl *impl;
-    std::call_once(of, [&](){
-        impl = mx25519_select_impl(MX25519_TYPE_AUTO);
-        if (!impl) {
+    static const mx25519_impl *impl = [](){
+        auto i = mx25519_select_impl(MX25519_TYPE_AUTO);
+        if (!i) {
             LOGERR(0, "Failed to select mx25519 implementation - unsupported platform");
             PANIC_STOP();
         }
-    });
+        return i;
+    }();
     return impl;
 }