[PATCH 1/2 rumpkernel] Weaken rumpuser symbols

Enable rumpuser_malloc and rumpuser_free functions to be overloaded
locally.

diff -urN rumpkernel.orig/debian/patches/rumpuser-mem.diff rumpkernel/debian/patches/rumpuser-mem.diff
--- rumpkernel.orig/debian/patches/rumpuser-mem.diff	1970-01-01 01:00:00.000000000 +0100
+++ rumpkernel/debian/patches/rumpuser-mem.diff	2026-05-01 20:29:37.000000000 +0100
@@ -0,0 +1,18 @@
+--- rumpkernel.orig/buildrump.sh/src/lib/librumpuser/rumpuser_mem.c	2026-05-01 20:24:48.000000000 +0100
++++ rumpkernel/buildrump.sh/src/lib/librumpuser/rumpuser_mem.c	2026-05-01 12:42:29.368993165 +0100
+@@ -43,6 +43,7 @@
+ 
+ #include "rumpuser_int.h"
+ 
++__attribute__((weak))
+ int
+ rumpuser_malloc(size_t howmuch, int alignment, void **memp)
+ {
+@@ -66,6 +67,7 @@
+ }
+ 
+ /*ARGSUSED1*/
++__attribute__((weak))
+ void
+ rumpuser_free(void *ptr, size_t size)
+ {
diff -urN rumpkernel.orig/debian/patches/series rumpkernel/debian/patches/series
--- rumpkernel.orig/debian/patches/series	2026-05-01 20:28:17.000000000 +0100
+++ rumpkernel/debian/patches/series	2026-05-01 20:31:34.000000000 +0100
@@ -30,3 +30,4 @@
 rump_bus_dma
 hci_shared_intr
 nonstring
+rumpuser-mem.diff