gsubprocess: Add G_SUBPROCESS_FLAGS_SEARCH_PATH_FROM_ENVP
If the launcher flag G_SUBPROCESS_FLAGS_SEARCH_PATH_FROM_ENVP
is set and
path lookup is performed (argv[0]
does not contain a /
), we use the
PATH
of the child instead of the parent.
_GSubprocessLauncher::path_from_envp
is removed because it is never
written to.