Build and run examples as tests

This PR turns examples into tests:

• Autotools: option --enable-examples is removed, the examples are built and run with make check;
• CMake: option MTIME_BUILD_EXAMPLES is removed, the examples are built with make and run with make test when -DBUILD_TESTING=ON.

Depends on !76 (merged).

examples/CMakeLists.txt

@@ -23,6 +23,7 @@ set(examples_Fortran
 
 foreach(example IN LISTS examples_Fortran)
   add_executable(${example} ${example}.f90)
+  add_test(NAME ${example} COMMAND ${example})
 endforeach()
 
 set(examples_C
@@ -34,6 +35,7 @@ set(examples_C
 
 foreach(example IN LISTS examples_C)
   add_executable(${example} ${example}.c)
+  add_test(NAME ${example} COMMAND ${example})
 endforeach()
 
 # Additional sources of the example executables: