Fixing gflags HINTS variable names (adding missing “_DIR”).

- The HINTS variables for gflags were incorrectly used as
  GFLAGS_[INCLUDE/LIBRARY]_HINTS when they should have been
  GFLAGS_[INCLUDE/LIBRARY]_DIR_HINTS as per the docs.
- Also removing a completed TODO in the main CMakeLists.
- Updating method of extracting current directory in CeresConfig.cmake
  to avoid use of CMAKE_CURRENT_LIST_DIR, which was not present in
  CMake =< v2.8.3.

Change-Id: I42ae696e3b785febe48688d912f0f343e8947cb0

CMakeLists.txt

@@ -103,7 +103,6 @@ OPTION(CUSTOM_BLAS
        ON)
 # Multithreading using OpenMP
 OPTION(OPENMP "Enable threaded solving in Ceres (requires OpenMP)" ON)
-# TODO(sameeragarwal): Replace this with a positive option instead?
 
 # Line search minimizer is useful for large scale problems or when
 # sparse linear algebra libraries are not available. If compile time,

cmake/CeresConfig.cmake.in

@@ -77,7 +77,8 @@ MACRO(CERES_REPORT_NOT_FOUND REASON_MSG)
 ENDMACRO(CERES_REPORT_NOT_FOUND)
 
 # Get the (current, i.e. installed) directory containing this file.
-SET(CURRENT_CONFIG_INSTALL_DIR ${CMAKE_CURRENT_LIST_DIR})
+GET_FILENAME_COMPONENT(CURRENT_CONFIG_INSTALL_DIR
+  "${CMAKE_CURRENT_LIST_FILE}" PATH)
 
 # Record the state of the CMake module path when this script was called so
 # that we can ensure that we leave it in the same state on exit as it was

cmake/FindGflags.cmake

@@ -103,7 +103,7 @@ LIST(APPEND GFLAGS_CHECK_LIBRARY_DIRS
 # Search supplied hint directories first if supplied.
 FIND_PATH(GFLAGS_INCLUDE_DIR
   NAMES gflags/gflags.h
-  PATHS ${GFLAGS_INCLUDE_HINTS}
+  PATHS ${GFLAGS_INCLUDE_DIR_HINTS}
   ${GFLAGS_CHECK_INCLUDE_DIRS})
 IF (NOT GFLAGS_INCLUDE_DIR OR
     NOT EXISTS ${GFLAGS_INCLUDE_DIR})
@@ -114,7 +114,7 @@ ENDIF (NOT GFLAGS_INCLUDE_DIR OR
        NOT EXISTS ${GFLAGS_INCLUDE_DIR})
 
 FIND_LIBRARY(GFLAGS_LIBRARY NAMES gflags
-  PATHS ${GFLAGS_LIBRARY_HINTS}
+  PATHS ${GFLAGS_LIBRARY_DIR_HINTS}
   ${GFLAGS_CHECK_LIBRARY_DIRS})
 IF (NOT GFLAGS_LIBRARY OR
     NOT EXISTS ${GFLAGS_LIBRARY})