ena(4): destroy all wait_event

Code contributed by KUSABA Takeshi <t-kusaba@iij.ad.jp>

ena(4): prevent AENQ handler from use-after-free

Code contributed by KUSABA Takeshi <t-kusaba@iij.ad.jp>

ena(4): replace malloc(9) to kmem(9)

Code contributed by KUSABA Takeshi <t-kusaba@iij.ad.jp>

branches: 1.1.1;
Initial revision