Add paranoia checks into the blkid, ext2fs, and ss libraries to ignore

Add paranoia checks into the blkid, ext2fs, and ss libraries to ignore
environment variables if the libraries are called from setuid or setguid
programs, or if kernel believes that the process is not eligible to create
a core dump.  In addition, if the libc has __secure_getenv(), use it so that
the libc can also do any additional limitations regarding when libraries can
trust environment variables (i.e., to integrate with systems like SELinux
and Posix capabilities).