fix: update examples to the one-parameter nec_geometry_complete

[charlieh0tel]

nec_geometry_complete() dropped its unused second parameter — CHANGELOG: "nec_geometry_complete() now takes only one parameter. The second parameter was unused." The Python examples and the test harness were updated with it; the C and Ruby examples were not.

The result is that example/test_nec.c does not compile against the shipped libnecpp.h:

example/test_nec.c:24:20: error: too many arguments to function 'nec_geometry_complete'
   24 |   NEC_ERROR_HANDLE(nec_geometry_complete(nec, 1, 0));
      |                    ^~~~~~~~~~~~~~~~~~~~~
src/libnecpp.h:201:6: note: declared here
  201 | long nec_geometry_complete(nec_context* in_context, int gpflag);

Three call sites in example/test_nec.c, one in example/test.rb.

Verification

With this change test_nec.c builds clean under -Wall and runs correctly against the installed library:

Gain: 8.407404, -1.958237 +/- 16.108164 dB
Impedance: 595.415366, -354.438287
Gain: 6.328267, 2.175237 +/- 3.240539 dB

Found while building nec2++ to WebAssembly — the examples are the natural reference for the C API, so the first thing tried was the first thing that didn't compile.

[charlieh0tel]

Closing — opened prematurely on my side; I'll route this through my own fork first.

[charlieh0tel]

Reopened — this is active. Disregard the closing note above.