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.
 */

#include <stdio.h>
#include <ffi.h>

int main(int argc, char *argv[])
{
    ffi_cif cif;
    ffi_type *args[1];
    void *values[1];
    char *s;
    int rc;

    (void)argc;
    (void)argv;

    args[0] = &ffi_type_pointer;
    values[0] = &s;

    if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, 1,
                           &ffi_type_uint, args) == FFI_OK)
    {
        s = "Hello World!";
        ffi_call(&cif, FFI_FN(puts), &rc, values);
        s = "Goodbye!";
        ffi_call(&cif, FFI_FN(puts), &rc, values);
    }

    return 0;
}