Simplify ASTConverter's conversion of binary expressions.

We can't rely on the operands' types for determining possible operations when considering non-deterministic values or function calls.
As each operator for numeric or boolean operations has a distinctive name, don't check anything but just convert these.




git-svn-id: https://svn.sosy-lab.org/software/cpachecker/trunk@14426 4712c6d2-40bb-43ae-aa4b-fec3f1bdfe4c