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             := src-msys-perl
$(PKG)_IGNORE   :=
$(PKG)_VERSION  := 5.8.8-1
$(PKG)_CHECKSUM := 2510a7ff6bf9486d0ffe51f86f8b4a57366c809c
$(PKG)_REMOTE_SUBDIR := perl/perl-$($(PKG)_VERSION)
$(PKG)_SUBDIR   := 
$(PKG)_FILE     := perl-$($(PKG)_VERSION)-msys-1.0.17-src.tar.lzma
$(PKG)_URL      := $(MSYS_EXTENSION_URL)/$($(PKG)_REMOTE_SUBDIR)/$($(PKG)_FILE)/download
$(PKG)_DEPS     := 

define $(PKG)_UPDATE
    $(WGET) -q -O- '$(MSYS_EXTENSION_URL)/perl' | \
    $(SED) -n 's,.*title="perl-\([0-9][^"]*\)".*,\1,p' | \
    head -1
endef

define $(PKG)_BUILD
endef