Bug report

Bug description:

Building 3.14.5 with gcc 15.2 and --enable-bolt produces this warning:

    default: BOLT-WARNING: specifying numeric value "1" for option -icf is deprecated

This line in configure.ac hard codes -icf=1 in BOLT_APPLY_FLAGS:

This issue mentions ICF behavior: #134642

Build environment: Ubuntu 26.04 LTS, gcc 15.2.0, configure with:

./configure --enable-optimizations --with-lto --enable-bolt --enable-safety --enable-slower-safety --with-system-expat CXX=/usr/bin/g++ CFLAGS="-flto=auto" LDFLAGS="-flto=auto"

CPython versions tested on:

3.14

Operating systems tested on:

Linux