Because you inadvertently specified the dynamic library by putting the -liomp5 option in the command line. By default the linker first searches for the shared variant of any libraries that you specify. You need -Bstatic before that -l option if you want the linker to search for the static variant.

But why do you have that -l option, or the -L option there at all? The compiler driver manages that sort of stuff for you.

There is no longer a static version of the OpenMP library, so the compiler will always use the dynamic OpenMP library when you use OpenMP. This is the case even if you compile you specify static.