The need for casting negative syscall arguments depends on the
glibc version. This affects the rules for the openat syscall which
uses the constant AT_FDCWD that is defined as a negative number.
This commit adds logic to only apply the cast when necessary, on
glibc versions from 2.27 onwards.

Different versions of glibc use either open or openat for the
opendir function. This commit adds logic to use the correct rule
for each glibc version, namely:
- Until 2.14 open is used
- From 2.15 to to 2.21 openat is used
- From 2.22 to 2.26 open is used
- From 2.27 onwards openat is used

Fix crash introduced in #40020. On startup, tor calls
check_private_dir on the data and key directories. This function
uses open instead of opendir on the received directory. Data and
key directoryes are only opened here, so the seccomp rule added
should be for open instead of opendir, despite the fact that they
are directories.