[Tizen] Correct default TEC path for 64-bit

The TEC extensions libraries are delivered into different directory
varies 32-bit (/usr/lib) and 64-bit (/usr/lib64), the default path need
to aware this difference. And use char[] instead of static std::string.

BUG=XWALK-1624
Merge pull request #1977 from halton/tec64

[Tizen] Correct default TEC path for 64-bit