Which sage-7.4 did you download ? If you downloaded binaries (which sould possible since you can run ./sage without error mesage), you do not have to run configure nor make, you just have to unpack the tarball and Sage will work.
Let me suggest tu restart fresh by unpacking the tarball. Now, to install cryptominisat, you just have to do:
./sage -i cryptominisat

Note that cryptominisat currently does not build on 32bit architectures.