Because we were previously converting the bytes in the format
string into Rust's char type and then printing that using the
format machinery, byte values that were not valid single-byte
UTF-8 characters failed to print correctly.  I found this while
trying to implement qsort() because the output of my test program
was mysteriously incorrect despite it working when I used glibc.

Signed-off-by: Marat Safin <jeizsm@gmail.com>

add gmtime and difftime

ci: Ensure that the correct compiler is installed

Ensure that a compiler is installed when the aarch64 CI build is run.

Run ./fmt.sh

Add mem* functions to stdio
Add constant int functions

stdio: Implement rename