Fix layer's memory errors

Fixes the wrong allocation of extensions properties.

Adds a call to the dispacher's DestroyInstance function before the
destruction of the instance.

Change-Id: I169bb3ba670d89e30af1f6ce47c536477978c169
Signed-off-by: Iason Paraskevopoulos <iason.paraskevopoulos@arm.com>
1 job for master in 1 minute and 17 seconds
Status Job ID Name Coverage
  Test
passed #5824522
build_vulkan_wsi_layer

00:01:17