LU-6210 gss: Change positional struct initializers to C99

LU-6210 gss: Change positional struct initializers to C99

This patch makes no functional changes.  Struct initializers in the
gss directory that use C89 or GCC-only syntax are updated to C99
syntax.  Whitespace is changed to match the coding style guidelines.

The C99 syntax prevents incorrect initialization if values are
accidently placed in the wrong position, allows changes in the struct
definition, and clears any members that are not given an explicit
value.

The following struct initializers have been updated:

lustre/ptlrpc/gss/gss_keyring.c:
	struct vfs_cred vcred (2 occurrences)
lustre/ptlrpc/gss/gss_krb5_mech.c:
	static struct krb5_enctype enctypes[]
lustre/ptlrpc/gss/gss_sk_mech.c:
	static struct gss_api_mech gss_sk_mech

Test-Parameters: trivial
Signed-off-by: Steve Guminski <stephenx.guminski@intel.com>
Change-Id: I87aecee88dc8c97df5f6892c08c914732d455356
Reviewed-on: https://review.whamcloud.com/23677
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>