system: Allow restricting the legacy DEVICE_NATIVE_ENDIAN definition

Guard the native endian definition we want to remove by surrounding
it with TARGET_NOT_USING_LEGACY_NATIVE_ENDIAN_API #ifdef'ry.
Assign values to the enumerators so they stay unchanged.

Once a target gets cleaned we'll set the definition in the target
config, then the target won't be able to use the legacy API anymore.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20260109165058.59144-21-philmd@linaro.org>

include/system/memory.h

@@ -27,9 +27,11 @@
 #include "qemu/rcu.h"
 
 enum device_endian {
-    DEVICE_NATIVE_ENDIAN,
-    DEVICE_BIG_ENDIAN,
-    DEVICE_LITTLE_ENDIAN,
+#ifndef TARGET_NOT_USING_LEGACY_NATIVE_ENDIAN_API
+    DEVICE_NATIVE_ENDIAN = 0,
+#endif
+    DEVICE_BIG_ENDIAN = 1,
+    DEVICE_LITTLE_ENDIAN = 2,
 };
 
 #define RAM_ADDR_INVALID (~(ram_addr_t)0)

system/memory-internal.h

@@ -41,9 +41,11 @@ void mtree_print_dispatch(struct AddressSpaceDispatch *d,
 /* returns true if end is big endian. */
 static inline bool devend_big_endian(enum device_endian end)
 {
+#ifndef TARGET_NOT_USING_LEGACY_NATIVE_ENDIAN_API
     if (end == DEVICE_NATIVE_ENDIAN) {
         return target_big_endian();
     }
+#endif
     return end == DEVICE_BIG_ENDIAN;
 }