[CMake] Add check for HAVE_KEYWORD_FINAL.

cmake/modules/CheckCXX11Features.cmake

@@ -342,4 +342,18 @@ check_cxx_source_compiles("
 " HAVE_CONSTEXPR
 )
 
+# keyword final
+check_cxx_source_compiles("
+  struct Foo
+  {
+    virtual void foo() final;
+  };
+
+  int main(void)
+  {
+    return 0;
+  }
+" HAVE_KEYWORD_FINAL
+)
+
 cmake_pop_check_state()

config.h.cmake

@@ -163,6 +163,9 @@
 /* Define to 1 if C++11 constexpr is supported */
 #cmakedefine HAVE_CONSTEXPR 1
 
+/* does the compiler support the keyword 'final'? */
+#cmakedefine HAVE_KEYWORD_FINAL 1
+
 /* Define to if the UMFPack library is available */
 #cmakedefine HAVE_UMFPACK ENABLE_UMFPACK