BSD user: suppress a warning

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

bsd-user/elfload.c

diff --git a/bsd-user/elfload.c b/bsd-user/elfload.c
index 06e6c63..19981f0 100644
--- a/bsd-user/elfload.c
+++ b/bsd-user/elfload.c
@@ -1107,10 +1107,10 @@
     s->disas_num_syms = nsyms;
 #if ELF_CLASS == ELFCLASS32
     s->disas_symtab.elf32 = syms;
-    s->lookup_symbol = lookup_symbolxx;
+    s->lookup_symbol = (lookup_symbol_t)lookup_symbolxx;
 #else
     s->disas_symtab.elf64 = syms;
-    s->lookup_symbol = lookup_symbolxx;
+    s->lookup_symbol = (lookup_symbol_t)lookup_symbolxx;
 #endif
     s->next = syminfos;
     syminfos = s;