Implement wcstol, wcstod, and printf:ing wchars

src/c_vec.rs

src/fs.rs

src/header/stdio/printf.rs

src/header/wchar/mod.rs

src/io.rs

tests/Makefile

tests/expected/netdb/getaddrinfo.stdout

tests/expected/netdb/netdb.stdout

tests/expected/wchar/printf-on-wchars.stderr

tests/expected/wchar/printf-on-wchars.stdout

tests/expected/wchar/wcstod.stderr

tests/expected/wchar/wcstod.stdout

tests/expected/wchar/wcstol.stderr

tests/expected/wchar/wcstol.stdout

tests/wchar/printf-on-wchars.c

tests/wchar/wcstod.c

tests/wchar/wcstol.c