Squashed 'features/nanostack/sal-stack-nanostack/' changes from 7963594..2535a6c
Squashed 'features/nanostack/sal-stack-nanostack/' changes from 7963594..2535a6c

2535a6c Merge branch 'release_internal' into release_external
6bc9e00 Merge pull request #1783 from ARMmbed/mac_fix
8b1577e Fixed possible memory leak at mac pd_sap_ind() function.

git-subtree-dir: features/nanostack/sal-stack-nanostack
git-subtree-split: 2535a6c779755a0dd1a50f14dc6a6902392c86ea

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