Backport: OMXNodeInstance: use a lock around OMX::freeNode

This is to avoid a concurrent use after free if other OMX commands
are being executed before the node is marked as deleted.

Bug: 63666573

Backport:
 Wrap into #ifndef/#endif statement to allow skipping this patch
 for specific devices by adding the following directive into the
 BoardConfig.mk or BoardConfigCommon.mk file of the device repo:
  TARGET_RELEASE_CPPFLAGS += -DSKIP_CVE_2017_13154

Change-Id: I7720dd900bfa252f8675e0c56191adbf52aa957e
CVE-2017-13154