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.

# This file is part of MXE.
# See index.html for further information.

PKG             := build-sed
$(PKG)_IGNORE   :=
$(PKG)_VERSION  := 4.8
$(PKG)_CHECKSUM := 61bd770062d49cdab3f0f45df473e2bf950ba266
$(PKG)_SUBDIR   := sed-$($(PKG)_VERSION)
$(PKG)_FILE     := sed-$($(PKG)_VERSION).tar.xz
$(PKG)_URL      := ftp://ftp.gnu.org/pub/gnu/sed/$($(PKG)_FILE)
$(PKG)_DEPS     := 

define $(PKG)_UPDATE
    $(WGET) -q -O- 'http://ftp.gnu.org/gnu/sed/?C=M;O=D' | \
    $(SED) -n 's,.*<a href="sed-\([0-9\.]*\)\.tar.*,\1,p' | \
    $(SORT) -V | \
    tail -1
endef

define $(PKG)_BUILD
    mkdir '$(1).build'
    cd    '$(1).build' && '$(1)/configure' \
        --prefix='$(BUILD_TOOLS_PREFIX)'
    $(MAKE) -C '$(1).build' -j '$(JOBS)'
    $(MAKE) -C '$(1).build' -j 1 install
endef