Fix compiler driver bug reading long dependency paths

[riftEmber]

Fix a bug causing the compiler driver to crash when working with dependency paths longer than 4096 characters.

Fixed by reading with std::getline which has no line length limit, rather than fgets which requires a (finite) buffer.

Resolves https://github.com/chapel-lang/chapel/issues/26261.

[reviewer info placeholder]

Testing:

• [ ] compiling program with >4096 character dependency paths
• [ ] paratest
• [ ] --no-compiler-driver paratest