BUILD: enhance --with-mpi to accept MPIHOME and MPIHOME/bin
BUILD: enhance --with-mpi to accept MPIHOME and MPIHOME/bin

also fix error message

shssf/ucx,sergsagal1/ucx_rocm,miked-mellanox/ucx,abouteiller/ucx,abouteiller/ucx,sergsagal1/ucx_rocm,sergsagal1/ucx_rocm,biddisco/ucx,abouteiller/ucx,abouteiller/ucx,manjugv/ucx,miked-mellanox/ucx,manjugv/ucx,biddisco/ucx,shssf/ucx,biddisco/ucx,miked-mellanox/ucx,manjugv/ucx,shssf/ucx