Merge topic 'feature/message-indent'

5f6fd917a3 message(): Control indentation via CMAKE_MESSAGE_INDENT

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !3464

Help/variable/CMAKE_MESSAGE_INDENT.rst

@@ -0,0 +1,30 @@
+CMAKE_MESSAGE_INDENT
+--------------------
+
+The :command:`message` command joins the strings from this list and for
+log levels of ``NOTICE`` and below, it prepends the resultant string to
+each line of the message.
+
+Example:
+
+.. code-block:: cmake
+
+  list(APPEND listVar one two three)
+
+  message(VERBOSE [[Collected items in the "listVar":]])
+  list(APPEND CMAKE_MESSAGE_INDENT "  ")
+
+  foreach(item IN LISTS listVar)
+    message(VERBOSE ${item})
+  endforeach()
+
+  list(POP_BACK CMAKE_MESSAGE_INDENT)
+  message(VERBOSE "No more indent")
+
+Which results in the following output:
+
+  -- Collected items in the "listVar":
+  --   one
+  --   two
+  --   tree
+  -- No more indent