maintainer-feedback requested: [Bug 292869] x11/nvidia-driver: fix build with clang 21

Bugzilla Automation <[email protected]> has asked freebsd-x11 (Nobody)
<[email protected]> for maintainer-feedback:
Bug 292869: x11/nvidia-driver: fix build with clang 21
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=292869



--- Description ---
With clang 21 x11/nvidia-kmod fails to build, with errors similar to:

    cc	-O2 -pipe -fno-strict-aliasing -DNV_VERSION_STRING=\"580.126.09\"
-DNV_SPECTRE_V2=1 -Werror=undef  -Werror -D_KERNEL -DKLD_MODULE -nostdinc 
-Imachine -I/usr/src/sys/sys -I../common/inc -include
/wrkdirs/usr/ports/x11/nvidia-kmod/work/NVIDIA-FreeBSD-x86_64-580.126.09/src/nv
idia-modeset/opt_global.h
-I. -I/usr/src/sys -I/usr/src/sys/contrib/ck/include -fno-common 
-fno-omit-frame-pointer -mno-omit-leaf-frame-pointer
-fdebug-prefix-map=./machine=/usr/src/sys/amd64/include
-fdebug-prefix-map=./x86=/usr/src/sys/x86/include
-fdebug-prefix-map=./i386=/usr/src/sys/i386/include    -MD 
-MF.depend.nvidia-modeset-freebsd.o -MTnvidia-modeset-freebsd.o -mcmodel=kernel
-mno-red-zone -mno-mmx -mno-sse -msoft-float  -fno-asynchronous-unwind-tables
-ffreestanding -fwrapv -fstack-protector  -Wall -Wstrict-prototypes
-Wmissing-prototypes -Wpointer-arith -Wcast-qual -Wundef -Wno-pointer-sign
-D__printf__=__freebsd_kprintf__ -Wmissing-include-dirs
-fdiagnostics-show-option -Wno-unknown-pragmas -Wswitch
-Wno-error=tautological-compare -Wno-error=empty-body
-Wno-error=parentheses-equality -Wno-error=unused-function
-Wno-error=pointer-sign -Wno-error=shift-negative-value
-Wno-address-of-packed-member -Wno-format-zero-length	-mno-aes -mno-avx 
-std=gnu17 -c nvidia-modeset-freebsd.c -o nvidia-modeset-freebsd.o
    nvidia-modeset-freebsd.c:296:32: error: passing 'printf' format string
where 'freebsd_kprintf' format string is expected [-Werror,-Wformat]
      296 |	ret = vsnprintf(str, size, format, ap);
	  |				   ^

This is because the kernel headers rely on the `printf` attribute being
called `__printf__`, so that it can be redefined as `__freebsd_kprintf__`.

Change the `nvkms_snprintf` declaration in nvidia-modeset-os-interface.h
so they use `__printf__` instead, and add a similar attribute to
`nvkms_vsnprintf`.