Ensure build paths for dependencies are searched in FindPackage(Ceres)

- Append to hint locations used by FindPackage scripts for public
  dependencies (glog & Eigen) the locations of the dependencies when
  Ceres was built.
- This means that the user should not have to supply them again when
  using find_package(Ceres) even if they are installed in a
  non-standard location.

Change-Id: I9550de91025ba47f01f1ea3c3fefe80fe38d14ff

cmake/CeresConfig.cmake.in

diff --git a/cmake/CeresConfig.cmake.in b/cmake/CeresConfig.cmake.in
index 6044700..1a33656 100644
--- a/cmake/CeresConfig.cmake.in
+++ b/cmake/CeresConfig.cmake.in
@@ -126,6 +126,8 @@
 # Eigen.
 # Flag set during configuration and build of Ceres.
 SET(CERES_EIGEN_VERSION @EIGEN_VERSION@)
+# Append the locations of Eigen when Ceres was built to the search path hints.
+LIST(APPEND EIGEN_INCLUDE_DIR_HINTS @EIGEN_INCLUDE_DIR@)
 # Search quietly s/t we control the timing of the error message if not found.
 FIND_PACKAGE(Eigen ${CERES_EIGEN_VERSION} EXACT QUIET)
 IF (EIGEN_FOUND)
@@ -141,6 +143,10 @@
 # Glog.
 # Flag set during configuration and build of Ceres.
 SET(CERES_USES_MINIGLOG @MINIGLOG@)
+# Append the locations of glog when Ceres was built to the search path hints.
+LIST(APPEND GLOG_INCLUDE_DIR_HINTS @GLOG_INCLUDE_DIR@)
+GET_FILENAME_COMPONENT(CERES_BUILD_GLOG_LIBRARY_DIR @GLOG_LIBRARY@ PATH)
+LIST(APPEND GLOG_LIBRARY_DIR_HINTS ${CERES_BUILD_GLOG_LIBRARY_DIR})
 IF (CERES_USES_MINIGLOG)
   SET(MINIGLOG_INCLUDE_DIR ${CERES_INCLUDE_DIR}/ceres/internal/miniglog)
   IF (NOT EXISTS ${MINIGLOG_INCLUDE_DIR})