Add an explicit include for local_parameterization.h

Thanks to cooordz for reporting this.

Change-Id: I7d345404e362a94ff1eb433ad6b9dcc4960ba76d

include/ceres/gradient_problem.h

diff --git a/include/ceres/gradient_problem.h b/include/ceres/gradient_problem.h
index ae3ac4f..55a8be1 100644
--- a/include/ceres/gradient_problem.h
+++ b/include/ceres/gradient_problem.h
@@ -34,11 +34,11 @@
 #include "ceres/internal/macros.h"
 #include "ceres/internal/port.h"
 #include "ceres/internal/scoped_ptr.h"
+#include "ceres/local_parameterization.h"
 
 namespace ceres {
 
 class FirstOrderFunction;
-class LocalParameterization;
 
 // Instances of GradientProblem represent general non-linear
 // optimization problems that must be solved using just the value of