shell: inability to print 64-bit integers with newlib support

[e-rk]

Describe the bug
When CONFIG_NEWLIB_LIBC=y is used, the shell printf is unable to substitute the %lu specifier.

To Reproduce
Steps to reproduce the behavior:

1. cd samples/subsys/shell/shell_module

2. Add CONFIG_NEWLIB_LIBC=y to prj.conf

3. Add the following lines to any command handler:

    uint64_t val = 51;
    shell_print(shell, "Test: %" PRIu64, val);
   

4. west build -b nrf52840dk_nrf52840 -p && west flash

5. Execute the command

    uart:~$ demo ping
    pong
    Test: %lu
   

6. Observe, that %lu is displayed instead of a number.

Expected behavior
The specifier is correctly substituted with a 64-bit value.

Impact
Inability to print 64-bit values with the shell.

Logs and console output
Output shown above.

Environment (please complete the following information):

• OS: Linux
• Toolchain gcc-arm-none-eabi-9-2019-q4-major
• Commit SHA or Version used: 4d0750920b52e0ce8a3e188d08a1769ff7ec527b

Additional context
The value used to be printed correctly with values less than 2^32. git bisect points to:

e812ee6c213143fdc94c20de1b8d26db38cd0cc0 is the first bad commit
commit e812ee6c213143fdc94c20de1b8d26db38cd0cc0
Author: Peter Bigot <[email protected]>
Date:   Tue Aug 18 14:03:13 2020 -0500

    shell: support floating point output with newlib
    
    shell_fprintf requires that formatted output be emitted with a
    putchar()-like output function.  Newlib does not provide such a
    capability.  Zephyr provides two solutions: z_prf() which is part of
    minimal libc and handles floating point formatting, and z_vprintk()
    which is core and does not support floating point.
    
    Move z_prf() out of minimal libc into the core lib area, and use it
    unconditionally in the shell.
    
    Signed-off-by: Peter Bigot <[email protected]>

:040000 040000 e41e21bd573bb9bb8de892ef95003c599f7585a8 c1dca9a4609ed2b63ffc30b37e93d0d2519bc8e2 M	lib
:040000 040000 7e472664932e6743c012c193c2e2e3810b7d7051 3aa84564ef4ab80c739c9c8a3ee836591c642fa6 M	subsys

It appears, that the z_vprintk used previously could substitute %lu, but only up to 2^32-1. The z_prf also has this ability (without the limitation), but it is blocked behind CONFIG_MINIMAL_LIBC_LL_PRINTF which can't be enabled due to CONFIG_NEWLIB_LIBC=y.

[pabigot]

This was going to be fixed by #29171 but that got shot down. We don't have a way forward until the discussion in #29203 (comment) reaches resolution.

[github-actions]

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[pabigot]

Should be closed by #29876