maint: maint.mk fetch acx_pthread from protobuf project. Add acx-pthread.mp4.
Add DGTEST_HAS_PTHREAD flag for gtest when has pthread.
maint: Build libgmockgtest as check_ltlibraries for tests with gtest and gmock.
maint:  Exclude gmock and gtest from cpplint check. Include maint.mk
Makefile.am to enable maintener targets in eclipse CDT.
maint: Remove *.log from exclude eclipse CDT resources.
maint: Add -build/include_order in cpplint call.
maint: Configure tests/hellowrold_test.cc with gtest.