Reapply "Modify mjPLUGIN_LIB_INIT to use C runtime initializer."

This reverts commit 4e20999.

Author: havess

include/mujoco/mjplugin.h

@@ -182,39 +182,17 @@ struct mjSDF_ {
 };
 typedef struct mjSDF_ mjSDF;
 
-#if defined(__has_attribute)
-
-  #if __has_attribute(constructor)
-    #define mjPLUGIN_LIB_INIT __attribute__((constructor)) static void _mjplugin_init(void)
-  #endif  // __has_attribute(constructor)
-
+#if defined(__has_attribute) && __has_attribute(constructor)
+    #define mjPLUGIN_LIB_INIT                                                                 \
+      static void _mjplugin_init(void) __attribute__((constructor));                          \
+      static void _mjplugin_init(void)
 #elif defined(_MSC_VER)
-
-  #ifndef mjDLLMAIN
-    #define mjDLLMAIN DllMain
-  #endif
-
-  #if !defined(mjEXTERNC)
-    #if defined(__cplusplus)
-      #define mjEXTERNC extern "C"
-    #else
-      #define mjEXTERNC
-    #endif  // defined(__cplusplus)
-  #endif  // !defined(mjEXTERNC)
-
-  // NOLINTBEGIN(runtime/int)
-  #define mjPLUGIN_LIB_INIT                                                                 \
-    static void _mjplugin_dllmain(void);                                                    \
-    mjEXTERNC int __stdcall mjDLLMAIN(void* hinst, unsigned long reason, void* reserved) {  \
-      if (reason == 1) {                                                                    \
-        _mjplugin_dllmain();                                                                \
-      }                                                                                     \
-      return 1;                                                                             \
-    }                                                                                       \
-    static void _mjplugin_dllmain(void)
-  // NOLINTEND(runtime/int)
-
-#endif  // defined(_MSC_VER)
+    #pragma section(".CRT$XCU", read)
+    #define mjPLUGIN_LIB_INIT                                                                 \
+      static void _mjplugin_init(void);                                                       \
+      __pragma(warning(suppress: 4189)) __declspec(allocate(".CRT$XCU")) static void (*_mjplugin_init_ptr)(void) = _mjplugin_init; \
+      static void _mjplugin_init(void)
+#endif
 
 // function pointer type for mj_loadAllPluginLibraries callback
 typedef void (*mjfPluginLibraryLoadCallback)(const char* filename, int first, int count);