mdist: fix error when running tests with a cross file
mdist: fix error when running tests with a cross file

Since commit 1420d0daceb10cafb52a7405f157032a5cc811a5 we use coredata's
cmd_line.txt handler to get the right setup arguments. But there's a bug
in that -- it mishandles cross/native files, producing invalid
descriptions of the command line. The only other place this was used,
though, is when generating meson-log.txt.

Fix it to produce correctly formatted arguments.

Fixes #10980

mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson