Print CMake messages on stdout rather than stderr

The default version of message("...") print to stderr, which is inappropriate
for informational messages such as the ones we are printing in these cases.

Using message(STATUS "...") makes these messages appear on stdout instead
which is more appropriate.

Change-Id: I02f41e6b4948e6938566f06d7164444bd5b8199e
Signed-off-by: Robert Hughes <robert.hughes@arm.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 89f0e5a..fe3240d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -518,7 +518,7 @@
 # object libs armnn to include in the build
 include(src/backends/backends.cmake)
 foreach(lib ${armnnLibraries})
-    message("Adding object library dependency to armnn: ${lib}")
+    message(STATUS "Adding object library dependency to armnn: ${lib}")
     list(APPEND armnn_sources $<TARGET_OBJECTS:${lib}>)
 endforeach()
 
@@ -826,7 +826,7 @@
     endif()
 
     foreach(lib ${armnnUnitTestLibraries})
-        message("Adding object library dependency to UnitTests: ${lib}")
+        message(STATUS "Adding object library dependency to UnitTests: ${lib}")
         list(APPEND unittest_sources $<TARGET_OBJECTS:${lib}>)
     endforeach()
 
@@ -838,7 +838,7 @@
 
     if(VALGRIND_FOUND)
         if(HEAP_PROFILING OR LEAK_CHECKING)
-            message("Valgrind is disabled for heap profiling and leak checking builds.")
+            message(STATUS "Valgrind is disabled for heap profiling and leak checking builds.")
         else()
             # Valgrind works with gperftools version number <= 2.4
             target_compile_definitions(UnitTests PRIVATE "WITH_VALGRIND=1")