Which line?  I'm symlinking both .a files.  from: http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/Tutorials/pdf/packages/SPICE_Tutorials_Merged.pdf

The default SPICE library names do not conform to the UNIX 
convention libname.a. So you cannot use the conventional 
library path/name options –L and –l, e.g. 
gcc … -L/path_to_libs/ -lname 
unless you rename the SPICE library.