pthread: backport pthread mutex related patches

pthread: backport pthread mutex related patches

This patch backports several commits from NuttX, that fixes pthread
mutex issues. Applying only one patch causes compilation errors. So
these patches are submitted in a single commit. All credits should go to
Gregory Nutt who wrote the original commits.

Change-Id: I5dfb4f68a253228fa55335dd6dd4e4413c690f45
Signed-off-by: Gregory Nutt <gnutt@nuttx.org>
[Song: backported a1fbc2ad, 2c37d369, 6e623ce0, fe03ef02, 5a69453e, 34c5e1c1, 8b23c16b, 86ab384d and 8b3c554e. from NuttX]
Signed-off-by: EunBong Song <eunb.song@samsung.com>