Introduce HAVE_TEUCHOS_EXECINFO into CMake

And only use backtrace() from 'execinfo.h' if HAVE_TEUCHOS_EXECINFO is
included.
FindEXECINFO in *BSD
Merge pull request #2 from isuruf/execinfo

FindEXECINFO in *BSD
Merge pull request #353 from certik/execinfo

Introduce HAVE_TEUCHOS_EXECINFO into CMake