Remove an optimization to not bother setting up the C++ compiler if we

weren't building the MPI C++ bindings because this causes "CXX=no" to
be passed to the mpicxx wrapper compiler.  

Unfortunately, this optimization was brought to the v1.7 branch, and
therefore if you --disable-mpi-cxx on the v1.7 branch, the same
problem will happen.  So this needs to be CMR'ed to v1.7 as well.

Submitted by Jeff, reviewed by Brian.  RM approved by Brian.

Fixes trac:4120.

cmr=v1.7.4:reviewer=ompi-gk1.7:subject=Fix mpicxx wrapper compiler

This commit was SVN r30302.

The following Trac tickets were found above:
  Ticket 4120 --> https://svn.open-mpi.org/trac/ompi/ticket/4120

configure.ac

@@ -1267,9 +1267,11 @@ fi
 # a helpful tip from Dave Goodell, set the precious variables for
 # compilers to "no" that we don't want.  Libtool's m4 configry will
 # interpret this as "I won't be using this language; don't bother
-# setting it up."
+# setting it up."  Note that we do this only for Fortran; we *don't*
+# do this for C++, because even if we're not building the MPI C++
+# bindings, we *do* still want to setup the mpicxx wrapper if we have
+# a C++ compiler.
 AS_IF([test "$OMPI_WANT_FORTRAN_BINDINGS" != "1"],[F77=no FC=no])
-AS_IF([test "$WANT_MPI_CXX_SUPPORT" != "1"],[CXX=no])
 
 LT_CONFIG_LTDL_DIR([opal/libltdl], [subproject])
 LTDL_CONVENIENCE