Fix harmless unused parameters warnings in builds without wxLogTrace().

Fix warnings appearing when building with --disable-debug under Unix by
either referencing the parameters or variables which become unused then,
because wxLogTrace() calls are compiled out, or by not compiling the code
whose only purpose is to call wxLogTrace() at all.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@76787 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
No real changes, just fix a harmless warning under OS X.

Don't use "size" variable unnecessarily under non-Mac platforms, this also
fixes a warning about reassigning it immediately after assigning a previous
values to it under Mac.

Closes #16353.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@76788 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775