autofs: fix do_install failure and remove unused /var/run directory

If ${D}/run doesn't exist, the following statement will have non-zero
exit code, which leads to do_install failure.
     test -d ${D}/run && rmdir ${D}/run

Modify it to use the if statement to make the do_install task succeed
no matter ${D}/run exists or not.

Also, this patch removes the unused /var/run directory. Leaving that
directory there will result in /run directory created before splitting
package, which in turn lead to 'installed-vs-shipped' QA error or QA
warning.

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Joe MacDonald <joe@deserted.net>