[r17-2973 Regression] FAIL: gcc.target/i386/builtin_target.c (test for excess errors) on Linux/x86_64

On Linux/x86_64,

9ab915926a4112475f1374498b1c7f6b9e39bb62 is the first bad commit
commit 9ab915926a4112475f1374498b1c7f6b9e39bb62
Author: Dipesh Sharma <[email protected]>
Date:   Sun Jul 19 14:49:15 2026 +0530

    Add ISA support for AVX10_V2_AUX and FP32 to FP8 single-source RTNE converts.

caused

FAIL: gcc.target/i386/builtin_target.c (test for excess errors)

with GCC configured with

../../gcc/configure --prefix=/export/users3/haochenj/src/gcc-bisect/master/master/r17-2973/usr --enable-clocale=gnu --with-system-zlib --with-demangler-in-ld --with-fpmath=sse --enable-languages=c,c++,fortran --enable-cet --without-isl --enable-libmpx x86_64-linux --disable-bootstrap

To reproduce:

$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/builtin_target.c --target_board='unix{-m32}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/builtin_target.c --target_board='unix{-m32\ -march=cascadelake}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/builtin_target.c --target_board='unix{-m64}'"
$ cd {build_dir}/gcc && make check RUNTESTFLAGS="i386.exp=gcc.target/i386/builtin_target.c --target_board='unix{-m64\ -march=cascadelake}'"

(Please directly reply to this email for question about this report.)
(If you met problems with cascadelake related, disabling AVX512F in command line might save that.)
(However, please make sure that there is no potential problems with AVX512.)