mkbuildtree:
Minor fix to mkbuildtree script.
## subdirectories.
# This first symlink is special: it links to shared files in Xen's source tree
-rm -f ${AD}/include/asm-xeno/hypervisor-ifs
-mkdir ${AD}/include/asm-xeno/hypervisor-ifs
-cd ${AD}/include/asm-xeno/hypervisor-ifs
+rm -rf ${AD}/include/asm-xeno/hypervisor-ifs
+mkdir ${AD}/include/asm-xeno/hypervisor-ifs
+cd ${AD}/include/asm-xeno/hypervisor-ifs
${AS}/lndir-rel -silent ../../../${RS}/../xen/include/hypervisor-ifs
# The remainder are the i386 -> xeno-i386 links