This fixes a compilation issue due to a missing forward declaration of
_getentropy() by just adding it directly to the source code. This patch
should be dropped once the issue is fixed upstream.
diff --color -rupN a/newlib/libc/reent/getentropyr.c b/newlib/libc/reent/getentropyr.c
--- a/newlib/libc/reent/getentropyr.c	2023-09-19 10:47:57.000000000 +0200
+++ b/newlib/libc/reent/getentropyr.c	2024-06-17 10:30:43.013582277 +0200
@@ -45,6 +45,9 @@ _getentropy_r (struct _reent *ptr,
   int ret;
 
   errno = 0;
+  /* Implemented in libgloss/libnosys/getentropy.c. Patching in forward
+   * declaration as quick compilation fix */
+  extern int _getentropy(void *buf, size_t buflen);
   if ((ret = _getentropy (buf, buflen)) == -1 && errno != 0)
     _REENT_ERRNO(ptr) = errno;
   return ret;