remove hdb ldap create declarations

The hdb_ldap_create and hdb_ldapi_create prototypes use the "static"
keyword, but the functions themselves are not implemented as static.

Heimdal's buildsystem dynamically adds function declarations to
hdb-protos.h based on the actual function implementations. Those
declarations in hdb-protos.h are not declared as static.

Since the build system generates the declarations dynamically, just
remove them from hdb-ldap.c.

(cherry picked from commit 10519ce50d3aaa8e40bb9e1e0dee5da847648f42)
Merge pull request #90 from ktdreyer/ldap-declaration-1-6-branch

1.6 cherry-pick: remove hdb ldap create declarations