Make no libusb build clearer

[will-v-pi]

Fix info and config help text without libusb, add no USB support messages to command line parsing errors, and add no USB support message to picotool version

$ picotool version
picotool v2.1.2-develop (Linux, GNU-12.2.0, RelWithDebInfo)

This version of picotool was compiled without USB support. Some commands are not available.

Eg, the output from picotool info is now

$ picotool info

ERROR: missing <filename>

SYNOPSIS:
    picotool info [-b] [-m] [-p] [-d] [--debug] [-l] [-a] <filename> [-t <type>]

Use "picotool help info" for more info

This version of picotool was compiled without USB support. Some commands are not available.

or picotool load

$ picotool load

ERROR: Unknown command: load

COMMANDS:
    info        Display information from the target file.
    config      Display or change program configuration settings from the target file.
    encrypt     Encrypt the program.
    seal        Add final metadata to a binary, optionally including a hash and/or signature.
    link        Link multiple binaries into one block loop.
    otp         Commands related to the RP2350 OTP (One-Time-Programmable) Memory
    partition   Commands related to RP2350 Partition Tables
    uf2         Commands related to UF2 creation and status
    version     Display picotool version
    coprodis    Post-process coprocessor instructions in disassembly files.
    help        Show general help or help for a specific command

Use "picotool help <cmd>" for more info

This version of picotool was compiled without USB support. Some commands are not available.

Fixes #245

[lurch]

Might also be worth modifying the get_doc for the help_command ?

[will-v-pi]

Might also be worth modifying the get_doc for the help_command ?

Do you mean this bit?

$ picotool help
PICOTOOL:
    Tool for interacting with RP-series device(s) in BOOTSEL mode, or with an RP-series binary

This already changes when you don't have libusb to

$ picotool help
PICOTOOL:
    Tool for interacting with an RP-series binary

[lurch]

This already changes when you don't have libusb to

$ picotool help
PICOTOOL:
    Tool for interacting with an RP-series binary

Yeah, I was thinking that it might be nice to also display the "This version of picotool was compiled without USB support. Some commands are not available." text when running picotool help? (Following the "better to be explicit than implicit" principle 😉 )

[will-v-pi]

This already changes when you don't have libusb to

$ picotool help
PICOTOOL:
    Tool for interacting with an RP-series binary

Yeah, I was thinking that it might be nice to also display the "This version of picotool was compiled without USB support. Some commands are not available." text when running picotool help? (Following the "better to be explicit than implicit" principle 😉 )

Ah, I'd actually been explicit not to do that (the if (!help_mode) line), to avoid contaminating the output of valid commands? With the current change, it only gets printed when you either do something invalid, or with picotool version which seemed like a tidier place to put it

[lurch]

Super minor nitpick, but IMHO libusb_not_found_message makes it sound like it's looking for libusb at runtime? built_without_libusb_message might be slightly better? 🤷