Depending on the host C++ compiler GCC13 fails on riscv configurations
with the following error
src/gcc/gcc/config/riscv/genrvv-type-indexer.cc:118:30: error: no member named 'log2' in namespace 'std'; did you mean simply 'log2'?
elmul_log2 = lmul_log2 - std::log2 (sew / eew);
^~~~~~~~~
log2
/usr/include/c++/v1/math.h:1463:1: note: 'log2' declared here
log2(_A1 __lcpp_x) _NOEXCEPT {return ::log2((double)__lcpp_x);}
^
Bring in an upstream fix for the build error.
Signed-off-by: Chris Packham <judge.packham@gmail.com>