build: set c standard via CMAKE_C_FLAGS

Otherwise -std=c99 is set for C++ files as well and g++ complains about
that.

Change-Id: I398e1b227fc07622ef10bbfca04e9cc44b146a4d
Signed-off-by: Christian Himpel <christian.himpel@intel.com>
build: use -std=c++0x for c++ files

Change-Id: If45290b52282a8f0593fed3936969e418c629887
Signed-off-by: Christian Himpel <christian.himpel@intel.com>
libipt: add c++ usage test

Change-Id: I81eef620dd5417b5282d92bf2cd66892ff9b1db6
Signed-off-by: Christian Himpel <christian.himpel@intel.com>