Ubuntu-focal: fails to build gmp

[tobiasdiez]

https://github.com/sagemath/sage/actions/runs/15888768084/job/44806968404:

   [gmp-6.3.0]   ::group::.log
  [gmp-6.3.0]   [spkg-install] Building a 64-bit version of GMP.
  [gmp-6.3.0]   [spkg-install] Building GMP with the C++ interface and (also) static libraries.
  [gmp-6.3.0]   [spkg-install] ** Building with "fat binary" support for 64-bit CPUs **
  [gmp-6.3.0]   [spkg-install] Checking what CFLAGS GMP would use if they were empty...
  [gmp-6.3.0]   [spkg-install] checking build system type... zen3-pc-linux-gnu
  [gmp-6.3.0]   [spkg-install] checking host system type... zen3-pc-linux-gnu
  [gmp-6.3.0]   [spkg-install] checking for a BSD-compatible install... /usr/bin/install -c
  [gmp-6.3.0]   [spkg-install] checking whether build environment is sane... yes
  [gmp-6.3.0]   [spkg-install] checking for a thread-safe mkdir -p... /usr/bin/mkdir -p
  [gmp-6.3.0]   [spkg-install] checking for gawk... no
  [gmp-6.3.0]   [spkg-install] checking for mawk... mawk
  [gmp-6.3.0]   [spkg-install] checking whether make sets $(MAKE)... yes
  [gmp-6.3.0]   [spkg-install] checking whether make supports nested variables... yes
  [gmp-6.3.0]   [spkg-install] checking whether to enable maintainer-specific portions of Makefiles... no
  [gmp-6.3.0]   [spkg-install] checking ABI=64
  [gmp-6.3.0]   [spkg-install] checking compiler gcc -O2 -pedantic -fomit-frame-pointer -m64 ... no, long long reliability test 1
  [gmp-6.3.0]   [spkg-install] configure: error: could not find a working compiler, see config.log for details
  [gmp-6.3.0]   [spkg-install] Error configuring GMP (with CFLAGS unset).
  [gmp-6.3.0]   [spkg-install] Consult /sage/local/var/tmp/sage/build/gmp-6.3.0/src/config.log for for details.
  [gmp-6.3.0]   ::endgroup::
  [gmp-6.3.0]   ************************************************************************
  [gmp-6.3.0]   Error installing package gmp-6.3.0