KokkosKernels: adding variable that returns version as a single number

This makes our code consistent with what Kokkos is doing and
provides users with an easy way to verify in their code that
a compatible version of Kokkos Kernels is being used.

CMakeLists.txt

@@ -26,6 +26,8 @@ IF(NOT KOKKOSKERNELS_HAS_TRILINOS)
   SET(KokkosKernels_VERSION_MAJOR 3)
   SET(KokkosKernels_VERSION_MINOR 5)
   SET(KokkosKernels_VERSION_PATCH 99)
+  SET(KokkosKernels_VERSION "${KokkosKernels_VERSION_MAJOR}.${KokkosKernels_VERSION_MINOR}.${KokkosKernels_VERSION_PATCH}")
+  MATH(EXPR KOKKOSKERNELS_VERSION "${KokkosKernels_VERSION_MAJOR} * 10000 + ${KokkosKernels_VERSION_MINOR} * 100 + ${KokkosKernels_VERSION_PATCH}")
 ENDIF()
 
 IF(${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.12.0")

cmake/KokkosKernels_config.h.in

@@ -8,6 +8,9 @@
 #endif
 // clang-format on
 
+/* Define the current version of Kokkos Kernels */
+#cmakedefine KOKKOSKERNELS_VERSION @KOKKOSKERNELS_VERSION@
+
 /* Define if fortran blas 1 function can return complex type */
 #cmakedefine KOKKOSKERNELS_TPL_BLAS_RETURN_COMPLEX