policycoreutils: mcstrans: use string_to_av_perm() to calculate permission access vector

mcstrans still uses CONTEXT__CONTAINS from av_permissions.h to calculate
a permission access vector. However, av_permissions.h was deprecated, so
it does not have access to the constant. This updates mcstrans to use
string_to_av_perm() to get the value for context contains.

Reported-by: Sven Vermeulen <sven.vermeulen@siphos.be>
Signed-off-by: Steve Lawrence <slawrence@tresys.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
libselinux: man: Add missing manpage links to security_load_policy.3

Add the missing manpage link for selinux_init_load_policy(3) and
selinux_mkload_policy(3) to security_load_policy(3)

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=753803

Acked-by: Steve Lawrence <slawrence@tresys.com>