Add testutils.c.
Add testutils.c.

msteinbeck/tinyspline,msteinbeck/tinyspline,msteinbeck/tinyspline,retuxx/tinyspline,retuxx/tinyspline,msteinbeck/tinyspline,msteinbeck/tinyspline,msteinbeck/tinyspline,msteinbeck/tinyspline,msteinbeck/tinyspline,retuxx/tinyspline