android-x86: fix building warnings of kitkat-x86

works also on arm platform, so...

Author:    Chih-Wei Huang <cwhuang@linux.org.tw>
Change-Id: Ic3ade475c5b92de26623e277170c71c49f9e41de
stat: fix printing selinux context and null-dereference

busybox stat tries to always print the selinux context, even if it
is not requested which leads to a segmentation fault due to
dereferencing a null-pointer.

This also changes the format-string used to print the context to
so it actually produces useful output.

Change-Id: Idfe15c931840457f357f860e560fca5b0480ad6f