Merge branches 'subdirs-simplify' and 'subdir-objects-pr10697' into maint

* subdirs-simplify:
  subdirs: unify rules for "cleaning" and "normal" recursive targets
  tests: add a "demo" test on C support

* subdir-objects-pr10697:
  subdir-objects: improve "make mostlyclean" efficiency and flexibility
  tests: look for '.lo' rather than '.o' object when using Libtool with C++
  cosmetics: few typofixes in older ChangeLogs, suggested by "codespell.py"

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>

diff --cc NEWS
index 19d19636c2cf440dab7056e8f64285309effb333,588e8ed497710cae4dc784c59a26e5b5cc13ef42..b61d58ad214b86ccb70780c19770198754581d3f
--- 1/NEWS
--- 2/NEWS
+++ b/NEWS
@@@ -62,14 -62,12 +62,20 @@@ New in 1.12.2
  
  * Cleaning rules:
  
 +  - Recursive cleaning rules descends into the $(SUBDIRS) in the natural
 +    order (as done by the other recursive rules), rather than in the
 +    inverse order.  They used to do that in order to work a round a
 +    limitation in an older implementation of the automatic dependency
 +    tracking support, but that limitation had been lifted years ago
 +    already, when the automatic dependency tracking based on side-effects
 +    of compilation had been introduced.
 +
+   - Cleaning rules for compiled objects (both "plain" and libtool) work
+     better when subdir objects are involved, not triggering a distinct
+     'rm' invocation for each such object.  They do so by removing *any*
+     compiled object file that is in the same directory of a subdir
+     object.  See automake bug#10697.
+ 
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  
  New in 1.12.1:

diff --cc t/list-of-tests.mk
Simple merge