* rfc1738.cc, rfc1738.h: Delete.
* csu_util/rfc1738.cc: Reimport latest version from upstream source.
Make thread-safe. Rewrite C++ wrapper in terms of std::string.
Document the divergences from the upstream source.
* csu_util/rfc1738.h: Recreate for the std::string version of the
C++ wrapper.
* Makefile.am (setup_SOURCES): Sync with added/removed files.
* IniParseFindVisitor.cc: Modify #includes.
(IniParseFindVisitor::visitFile): Change function name, as the new
C++ wrapper does not contain an irregularity that the old one did.
* download.cc: Modify #includes.
* ini.cc: Modify #includes.