citnames: use parallel stl

[rizsotto]

using parallel stl, but see no improvement in speed...

• replaced the for loop with a std::for_each call.
• passed the -ltbb as a linker flag.
• compared the speed with and without the change (no difference)
• monitored the process thread count with htop on linux (saw no extra threads)

[SunJun8]

It looks like std::execution::par doesn't take effect