Remove routines for making exports/linux.def

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Remove routines for generating exports/symbol.S

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Remove unused dll2 target

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Remove code for downloading lapack tarball and the patches themselves

They are not used anymore since 3eb5af1.

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
Merge branch 'TimothyGu-develop' into develop