Add a missing include dir to the cuda kernels target.

This was somehow overlooked in the last patch causing the cuda
built to break.

Change-Id: Ic447103b139f6a7b607d664d02b9cbae98072ace

internal/ceres/CMakeLists.txt

diff --git a/internal/ceres/CMakeLists.txt b/internal/ceres/CMakeLists.txt
index f5b8dec..0436178 100644
--- a/internal/ceres/CMakeLists.txt
+++ b/internal/ceres/CMakeLists.txt
@@ -131,7 +131,7 @@
   target_compile_definitions(ceres_cuda_kernels PRIVATE CERES_STATIC_DEFINE)
   # Enable __host__ / __device__ annotations in lambda declarations
   target_compile_options(ceres_cuda_kernels PRIVATE --extended-lambda)
-  target_include_directories(ceres_cuda_kernels PRIVATE  ${Ceres_SOURCE_DIR}/internal  ${Ceres_BINARY_DIR}/${CMAKE_INSTALL_INCLUDEDIR})
+  target_include_directories(ceres_cuda_kernels PRIVATE  ${Ceres_SOURCE_DIR}/include  ${Ceres_SOURCE_DIR}/internal ${Ceres_BINARY_DIR}/${CMAKE_INSTALL_INCLUDEDIR})
   list(APPEND CERES_LIBRARY_PRIVATE_DEPENDENCIES ceres_cuda_kernels)
 endif (USE_CUDA)