prevent silent failure of events integration test

src/tests/integration/events/async-hello.F90 was failing silently
with GCC 7.  This commit bumps the image count to 3 so the test
prints output that reports the fatal MPI error. This commit also
uses C preprocessor conditionals to prevent reporting success
for this test with GCC 7.  The pre-processor conditionals will
need to be removed manually when the silent failure has been
eliminated.

Author: Damian Rouson

CMakeLists.txt

@@ -399,7 +399,7 @@ if(opencoarrays_aware_compiler)
   add_mpi_test(hello_multiverse 2 ${tests_root}/integration/coarrayHelloWorld/hello_multiverse)
   add_mpi_test(coarray_burgers_pde 2 ${tests_root}/integration/pde_solvers/coarrayBurgers/coarray_burgers_pde)
   add_mpi_test(co_heat 2 ${tests_root}/integration/pde_solvers/coarrayHeatSimplified/co_heat)
-  add_mpi_test(asynchronous_hello_world 2 ${tests_root}/integration/events/asynchronous_hello_world)
+  add_mpi_test(asynchronous_hello_world 3 ${tests_root}/integration/events/asynchronous_hello_world)
   if ( ("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "x86_64") AND ("${CMAKE_SYSTEM_NAME}" MATCHES "Linux") )
     if ( (NOT (DEFINED ENV{TRAVIS})) AND (NOT SKIP_ASSEMBLY_DEPS) )
       add_mpi_test(coarray_navier_stokes 2 ${tests_root}/integration/pde_solvers/navier-stokes/coarray_navier_stokes)

src/tests/integration/events/CMakeLists.txt

@@ -1,2 +1,2 @@
-add_executable(asynchronous_hello_world async-hello.f90)
+add_executable(asynchronous_hello_world async-hello.F90)
 target_link_libraries(asynchronous_hello_world OpenCoarrays)

src/tests/integration/events/async-hello.f90 renamed to src/tests/integration/events/async-hello.F90

@@ -69,7 +69,11 @@ program main
     end do
 
     sync all
+! Hardwire failure with GCC 7 (remove this preprocessor conditional after the silent failure with GCC 7 has been eliminated)
+#if __GNUC__ >= 7
+#else
     if (me==1) print *,"Test passed."
+#endif
 
   end associate