- instead of C++ std::complex<>
- avoids running into problems mixing C99 and C++ headers
- GSL complex numbers should be binary-compatible with C99 complex
  numbers, so remove complex number tests in lalsuite_build.m4
- update SWIG wrappings to convert COMPLEX8/16 from GSL complex numbers
- convert old codes still using old complex structs for assignment to
  use C99 complex numbers, can now remove old complex structs completely
- refs #1105
Original: 3bb3c4f3b810694aef1f1c96323d3f3efd9b3dbe