OCI8: fix prototypes for oci_field_*().  They can take a column index or name.
Merge branch 'oci_field_doc_prototype_fixes' into PHP-5.6

* oci_field_doc_prototype_fixes:
  OCI8: fix prototypes for oci_field_*().  They can take a column index or name.
Merge branch 'PHP-5.6'

* PHP-5.6:
  OCI8: fix prototypes for oci_field_*().  They can take a column index or name.