maint: Follow Octave conventions for use of semicolon in BIST tests. * testfun.txi: Document Octave conventions for use of semicolon in BIST tests. * cellfun.cc, ellipj.cc, file-io.cc, gcd.cc, hash.cc, nproc.cc, utils.cc, fftw.cc, ov-usr-fcn.cc, oct-parse.in.yy, md5sum.m, wavread.m, wavwrite.m, cplxpair.m, rat.m, im2double.m, rref.m, stem3.m, rotate.m, pchip.m, blackman.m, hamming.m, hanning.m, spectral_adf.m, spectral_xdf.m, assert.m, fail.m, etime.m, build-sparse-tests.sh, classes.tst, ctor-vs-method.tst, index.tst, io.tst, struct.tst: Follow Octave conventions for use of semicolon in BIST tests.

--- a/scripts/signal/blackman.m	Fri Apr 01 16:03:29 2016 -0700
+++ b/scripts/signal/blackman.m	Fri Apr 01 18:16:01 2016 -0700
@@ -89,5 +89,5 @@
 %!error blackman (0.5)
 %!error blackman (-1)
 %!error blackman (ones (1,4))
-%!error blackman (1, "invalid");
+%!error blackman (1, "invalid")