net-fs/autofs: add USE=dmalloc support

this flag is for memory allocation debuggig
so we disable it by default

Signed-off-by: Lan Yixun (dlan) <dennis.yxun@gmail.com>
net-fs/autofs: set configure options explicitly

Signed-off-by: Lan Yixun (dlan) <dennis.yxun@gmail.com>
net-fs/autofs: live ebuild support

Signed-off-by: Lan Yixun (dlan) <dennis.yxun@gmail.com>