Change the order of link_args when cross_compiling with ninja.

A user may want to add libraries to link with in the (c|cpp)_link_args
property of the cross-compile file.
Those libraries should be at the end of the command line due to reference
resolution mechanism of the compiler.

By moving the cross_args after LINK_ARGS we are sure that specific
cross-compilation libraries are at the end of the command line.

See [github PR #1363](https://github.com/mesonbuild/meson/pull/1363) to
have the context of this change.

mesonbuild/backend/ninjabackend.py

@@ -1276,10 +1276,10 @@ int dummy;
                 if mesonlib.is_windows():
                     command_template = ''' command = {executable} @$out.rsp
  rspfile = $out.rsp
- rspfile_content = {cross_args} $ARGS  {output_args} $in $LINK_ARGS $aliasing
+ rspfile_content = $ARGS  {output_args} $in $LINK_ARGS {cross_args} $aliasing
 '''
                 else:
-                    command_template = ' command = {executable} {cross_args} $ARGS {output_args} $in $LINK_ARGS $aliasing\n'
+                    command_template = ' command = {executable} $ARGS {output_args} $in $LINK_ARGS {cross_args} $aliasing\n'
                 command = command_template.format(
                     executable=' '.join(compiler.get_linker_exelist()),
                     cross_args=' '.join(cross_args),