Remove unnecessarily copied structure

runtime.cc included a verbatim copy of the structure __locale_data
from glibc. We don't need it (not to mention that we're not supposed
to copy anything from glibc, it has the wrong license).

We previously believed that libstdc++ pokes into this structure, so it
needs to be in the exact format of glibc, but now I believe this is not
the case, and it only uses __nl_langinfo_l, which in our implementation
doesn't even adhere to the locale, and just uses the C locale.