Fixed compilation with Clang's libc++.
Fixed compilation with GCC 4.9.

Standards-conforming STL implementation has no implicit default
constructor for std::vector, making me write this ugly verbose code.
package: added Clang/libc++ and GCC 4.9 development PKGBUILDs.
package: add Clang/libc++ combination to Jenkins CI configuration.

Hello, shell? I hate you.