putc, puts, perror, vscanf and vsscanf from getting annotations.

Add annotations for eight printf functions, memalign, pread and pwrite.

On Linux, llvm-gcc sometimes renames strdup, getc, putc, strtok_r, scanf and
sscanf. Match the alternate function names.

Fix a crash annotating opendir.

Don't mark fsetpos's second parameter as nocapture. It's supposed to be
captured.

Do mark fopen's path and mode strings as nocapture. Mark ferror as readonly,
but not fileno which may set errno.

llvm-svn: 62456