maint: cleanup code in BIST tests to use Octave coding conventions. * data.cc: Use keyword "endfor" rather than bare "end". * file-io.cc, graphics.cc: Remove semicolon ';' at end of "end_try_catch" keyword. * variables.cc, bug-35448.tst, bug-53027.tst, bug-53579.tst, bug-53599.tst, bug-53956.tst, bug-55758.tst, global.tst: Use semicolon ';' after "global" variable declaration. * for.tst, io.tst: Delete semicolon ';' at end of "for" loop declaration. * struct.tst: Delete semicolon ';' at end of "function" declaration.

--- a/test/bug-35448/bug-35448.tst	Sun Nov 27 16:58:42 2022 -0500
+++ b/test/bug-35448/bug-35448.tst	Sun Nov 27 17:01:00 2022 -0800
@@ -24,14 +24,14 @@
 ########################################################################
 
 %!test <*35448>
-%! global gfun
+%! global gfun;
 %! gfun = @fB;
 %! y = fA (e);
 %! assert (y, e);
 %! clear -global gfun;  # cleanup after test
 
 %!test <*35448>
-%! global gfun
+%! global gfun;
 %! gfun = @fC;
 %! y = fA (e);
 %! assert (y, e);