Add build rule for build-octave (bug #49503). * src/build-octave.mk: Add new build rule for build-octave which can be used for cross-building binary packages that depend on Octave as a build tool. * dist-files.mk: Add new file to list. * index.html: Add new package to list. * src/of-communications.mk, src/of-image.mk, src/of-mapping.mk, src/of-optiminterp.mk, src/of-sparsersb.mk, src/of-statistics.mk, src/of-windows.mk: Add optional dependency on build-octave. * configure.ac: Add new configure switch "--disable-system-octave" that is needed to build the build-octave package. * Makefile.in: Add variable "USE_SYSTEM_OCTAVE". Exclude build-octave from the default build tools and build it only if a package explicitly depends on it. Display warning about missing native Octave version only if necessary.

diff -uNr a/include/libmp3lame.sym b/include/libmp3lame.sym
--- a/include/libmp3lame.sym	2017-09-06 19:33:35.000000000 +0000
+++ b/include/libmp3lame.sym	2019-01-25 18:35:48.099270155 +0000
@@ -1,5 +1,4 @@
 lame_init
-lame_init_old
 lame_set_num_samples
 lame_get_num_samples
 lame_set_in_samplerate