added gc_dyn_extend_pulse.vhd where the width of the extended pulse comes as an input rather than a generic.

gc_frequency_meter: use gc_pulse_synchronizer for external PPS pulse (in case the measured frequency is slower than the gating frequency)

0 is impossible, since it is the interconnect record
=> use it instead

The subrange type might not be known in this context.
Fixes:
  wishbone_pkg.vhd:1379:26: object subtype is not locally static