xsrc/56054: Xorg fails to start with 24-bit wsfb

[nia%pkgsrc.org@localhost]

>Number:         56054
>Category:       xsrc
>Synopsis:       Xorg fails to start with 24-bit wsfb
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    xsrc-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Mar 13 07:45:00 +0000 2021
>Originator:     nia
>Release:        NetBSD 9.1
>Organization:
>Environment:
NetBSD 9.1 amd64
>Description:
wsfb fails with a 24 bits per pixel vesa framebuffer, but a 24 bits per pixel vesa framebuffer is reasonale.
>How-To-Repeat:
- Boot NetBSD/amd64 in QEMU.
- Observe that QEMU does not allow "vesa 1024x768x32".
- Type "vesa 1024x768x24" followed by "boot" at the boot prompt.
- Log in as root and type startx.
- Xorg fails to initialize the wsfb driver, with the message "wsfb(0): Specified fbbpp (24) is not a permitted value".
- Observe that "vesa 1024x768x16" works, but is disappointing.
>Fix: