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 --git "a/netcdf/ncdump/ncvalidator.c" "b/netcdf/ncdump/ncvalidator.c"
index a0e4acb..2a7c5af 100644
--- "a/ncdump/ncvalidator.c"	
+++ "b/ncdump/ncvalidator.c"
@@ -76,7 +76,9 @@ THIS SOFTWARE.
 #ifdef _WIN32
 #include <io.h>
 #define snprintf _snprintf
+#ifndef HAVE_UNISTD_H
 #include "XGetopt.h"
+#endif
 int opterr;
 int optind;
 #endif