[cdi-tiles] changed locking mechanism st. the original vlist of a stream is locked as soon as it is attached to the stream.

[cdi-tiles] implemented auxiliary routine which simply checks if resource handle exists (without error message).

* The only user immediately destroyd the copy.

* Replace expensive function call with comparison.

* It's only in grib_api releases 1.12 and after.

* Also automatically find cfortran.h flag for as many platforms as we
  can test at the moment.