force use of C++ linker

[[Imported from SVN: r5776]]

lib/Makefile.am

@@ -5,6 +5,9 @@ lib_LTLIBRARIES = libdunecommon.la
 
 # this is just a renaming of libcommon to prevent name clashes
 libdunecommon_la_SOURCES =
+# This forces automake to use the C++ linker
+# (see the automake manual, section "Libtool Convenience Libraries")
+nodist_EXTRA_libdunecommon_la_SOURCES = dummy.cc
 libdunecommon_la_LIBADD = ../dune/common/libcommon.la
 
 include $(top_srcdir)/am/global-rules