[Autotools] Install DuneSymlinkOrCopy.cmake

Similar to last commit:
This macro was split off from DuneMacros.cmake in commit
e63ea0cf, but the new macro file was
not included in the list of installed modules.

cmake/modules/Makefile.am

@@ -15,6 +15,7 @@ MODULES = \
   DuneMPI.cmake           \
   DunePkgConfig.cmake     \
   DuneStreams.cmake       \
+  DuneSymlinkOrCopy.cmake \
   DuneTestMacros.cmake    \
   DuneTests.cmake         \
   FindBoostFusion.cmake   \