ringbuf: Fix ordering of StaticRingbuffer_t

When building on linux/host compilers (e.g., GCC), the compiler may add padding
depending on the size and order of the member types.

This commit fixes the ordering or the StaticRingbuffer_t such that it matches
the internal Ringbuffer_t. The "_Static_assert" is always enabled for all
compilers.

Closes https://github.com/espressif/esp-idf/issues/11726

components/esp_ringbuf/include/freertos/ringbuf.h

@@ -57,8 +57,8 @@ typedef struct xSTATIC_RINGBUFFER {
     /** @cond */    //Doxygen command to hide this structure from API Reference
     size_t xDummy1[2];
     UBaseType_t uxDummy2;
-    BaseType_t xDummy3;
-    void *pvDummy4[11];
+    void *pvDummy3[11];
+    BaseType_t xDummy4;
     StaticList_t xDummy5[2];
     void * pvDummy6;
     portMUX_TYPE muxDummy;