I have located the problem, it was of course between the keyboard and the chair. After compiling with the b2 command I mentionned, I was running a .\b2 install --prefix "mypath", a la make. This last command actually recompiled libraries in 32 bits. I did not notice because it starts spending a lot of time copying files, and also because options that are needed the first time b2 is called (like toolset) seems to be cached for the following calls of b2 while address-model is obviously not but has a default value of 32.

Another small remark: the documentation in 1.54.0 has changed and mention to run bootstrap/b2 from tool/build/v2, but when I run them from there, no binary is generated.

Thanks for your help Richard.