libarchive: Define __LA_DEPRECATED consistently

Upstream libarchive now defines this macro in two places with the same
logic in both.  However, CMake's bundled copy disables this macro, so
we need to update the new location of its definition to be consistent.

Utilities/cmlibarchive/libarchive/archive_entry.h

@@ -105,11 +105,8 @@ typedef int64_t la_int64_t;
 # define __LA_DECL
 #endif
 
-#if defined(__GNUC__) && __GNUC__ >= 3 && __GNUC_MINOR__ >= 1
-# define __LA_DEPRECATED __attribute__((deprecated))
-#else
-# define __LA_DEPRECATED
-#endif
+/* CMake uses some deprecated APIs to build with old libarchive versions.  */
+#define __LA_DEPRECATED
 
 #ifdef __cplusplus
 extern "C" {