hds: Tweak hdsDimC2F to simplify usage

Always copy to Fortran dims as this allows the code that
uses hdsDimC2F to be much simpler albeit with a small performance
hit. The Fortran array is now always filled.
extractor: track changes in submodule

Improve scamp compatibility
hds: Use DAT__FLEXT when testing creation of component with same name
hds: Fix hds test use of %VAL
hds: Remove trailing whitespace from exercise
extractor: Fix gitignore in submodule
extractor: minor re-ordering in configure.ac

"./configure" failed on Unbuntu system due to CC not being set. Have moved block
containing AC_PROG_CC to before STAR_MONOLITH macro.