syslinux: fixed to cross compile for 64bits

they define LD=ld -melf_i386, which we override, so we have to override it
correctly.

x86/syslinux/syslinux.conf

@@ -24,3 +24,6 @@ makeopt=
 var_remove GCC2_WRAPPER_INSERT ' ' "-fstack-protector"
 var_remove GCC3_WRAPPER_INSERT ' ' "-fstack-protector"
 
+# they define LD=ld -m elf_i386 on every Makefile, which we override.
+# $(CC) is called with -m32, so if we drop the -melf_i386, they wont link
+export LD="$LD -m elf_i386"