This changes libcc1 to use unique_ptr in a few more places, removing
some manual memory management.
libcc1
* libcp1.cc (struct libcp1) <connection, compilerp>: Use
unique_ptr.
(~libcp1): Remove.
(libcp1_compile, libcp1_set_triplet_regexp)
(libcp1_set_driver_filename): Update.
* libcc1.cc (struct libcc1) <connection, compilerp>: Use
unique_ptr.
(~libcc1): Remove.
(libcc1_set_triplet_regexp, libcc1_set_driver_filename)
(libcc1_compile): Update.