MFC r311227,r311917:

MFC r311227,r311917:

r311227:

seekdir_basic: fix various Coverity issues

Address..
- .. resource leaks of file descriptors and memory
- .. unchecked return values from creat(2), mkdir(2), and telldir(3)
- .. potential NULL derefs after calling readdir(3)

CID:		975255, 975256, 976989, 978989, 978990

r311917:

Fix up r311227

Check for creat returning a value != -1, not a non-zero value

Pointyhat to:	ngie
CID:		1368366

git-svn-id: svn://svn.freebsd.org/base/stable/10@312091 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f