Do test 'icb-exmm' on bionic which may have eigen 3.3 !

.travis.yml

@@ -135,7 +135,7 @@ jobs:
   # bionic <=> test "recent" systems, with ICB
   - stage: bionic
     dist: bionic
-    script: ./bootstrap && ./configure --enable-icb --enable-mpi && export VERBOSE=1 && make all && make check
+    script: ./bootstrap && ./configure --enable-icb --enable-icb-exmm --enable-mpi && export VERBOSE=1 && make all && make check
   - stage: bionic
     dist: bionic
     before_install:
@@ -151,11 +151,11 @@ jobs:
     - sudo updatedb
     script: |
       cd $TRAVIS_BUILD_DIR && mkdir -p build && cd build &&                                  \
-      cmake -DEXAMPLES=ON -DICB=ON -DMPI=ON -DPYTHON3=ON -DBOOST_PYTHON_LIBSUFFIX='36' .. && \
+      cmake -DEXAMPLES=ON -DICB=ON -DICBEXMM=ON -DMPI=ON -DPYTHON3=ON -DBOOST_PYTHON_LIBSUFFIX='36' .. && \
       export VERBOSE=1 && make all && make test
   # coverage: "recent" systems with ICB
   - stage: coverage
-    dist: xenial
+    dist: bionic
     script: |
       mkdir -p build && cd build                                                   \
       &&                                                                           \

CMakeLists.txt

@@ -75,7 +75,7 @@ if (PYTHON3)
 endif ()
 
 if (ICBEXMM)
-    find_package(Eigen3)
+    find_package(Eigen3 3.3)
     if (NOT EIGEN3_FOUND) # If not found, piggy-back pkg-config files.
         message(WARNING "CMake didn't find the Eigen3 package. Try to look for pkg-config file...")
         find_package(PkgConfig REQUIRED)