CERES_EXPORT fix to compile Ceres as DLL

Below fixes are required to compile Ceres as a dynamic library using
MSVC.
1. Added CERES_EXPORT to EigenQuaternionParameterization.
2. Removed CERES_EXPORT from CubicInterpolator and BicubicInterpolator.

EigenQuaternionParameterization has its source embedded in ceres.dll 
whereas Cubic+BicubicInterpolators are defined in the header file and 
therefore do not require __declspec(dllimport).

Change-Id: Idd1f387890c36aab51a1a4177ea7c06933b96f39

include/ceres/cubic_interpolation.h

diff --git a/include/ceres/cubic_interpolation.h b/include/ceres/cubic_interpolation.h
index 53bbc33..9804a33 100644
--- a/include/ceres/cubic_interpolation.h
+++ b/include/ceres/cubic_interpolation.h
@@ -121,7 +121,7 @@
 //  double f, dfdx;
 //  interpolator.Evaluator(1.5, &f, &dfdx);
 template<typename Grid>
-class CERES_EXPORT CubicInterpolator {
+class CubicInterpolator {
  public:
   explicit CubicInterpolator(const Grid& grid)
       : grid_(grid) {
@@ -253,7 +253,7 @@
 //  interpolator.Evaluate(1.2, 2.5, &f, &dfdr, &dfdc);
 
 template<typename Grid>
-class CERES_EXPORT BiCubicInterpolator {
+class BiCubicInterpolator {
  public:
   explicit BiCubicInterpolator(const Grid& grid)
       : grid_(grid) {

include/ceres/local_parameterization.h

diff --git a/include/ceres/local_parameterization.h b/include/ceres/local_parameterization.h
index 379fc68..046c6bd 100644
--- a/include/ceres/local_parameterization.h
+++ b/include/ceres/local_parameterization.h
@@ -222,7 +222,7 @@
 //
 // Plus(x, delta) = [sin(|delta|) delta / |delta|, cos(|delta|)] * x
 // with * being the quaternion multiplication operator.
-class EigenQuaternionParameterization : public ceres::LocalParameterization {
+class CERES_EXPORT EigenQuaternionParameterization : public ceres::LocalParameterization {
  public:
   virtual ~EigenQuaternionParameterization() {}
   virtual bool Plus(const double* x,