CMake: Bugfix

git-svn-id: https://svn.dealii.org/trunk@28879 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/cmake/configure/configure_1_mpi.cmake b/deal.II/cmake/configure/configure_1_mpi.cmake
index dd5bffa9156407c11a550d20a86016fa8e5e9cd5..cb1c2ed91dbf47257acc24d42e1b7d33a433e6d7 100644 (file)
--- a/deal.II/cmake/configure/configure_1_mpi.cmake
+++ b/deal.II/cmake/configure/configure_1_mpi.cmake
@@ -26,8 +26,8 @@ MACRO(FEATURE_MPI_FIND_EXTERNAL var)
   # If CMAKE_CXX_COMPILER is already an MPI wrapper, use it to determine
   # the mpi implementation:
   #
-  SET(MPI_C_COMPILER ${CMAKE_C_COMPILER})
-  SET(MPI_CXX_COMPILER ${CMAKE_CXX_COMPILER})
+  SET_IF_EMPTY(MPI_C_COMPILER ${CMAKE_C_COMPILER})
+  SET_IF_EMPTY(MPI_CXX_COMPILER ${CMAKE_CXX_COMPILER})
   FIND_PACKAGE(MPI)
 
   IF(NOT MPI_CXX_FOUND)