In France, it's not possible to download the English version of Visual Studio; hence CL.EXE presents itself as:
Compilateur d'optimisation Microsoft (R) 32 bits C/C++ version 16.00.30319.01 pour 80x86
instead of
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 16.00.30319.01 for 80x86

With a simple fix we can handle this in configure as well.