Merge branch 'master' into ng/master

* master:
  maintcheck: fix failures, both real and spurious
  subdir tests: avoid an use of "make -j4", for portability
  tests: avoid failure due to libtool quirks in C++ demo test
  tests: fix spurious failures due to missing '$sleep'
  subdirs: unify rules for "cleaning" and "normal" recursive targets
  tests: add a "demo" test on C support
  tests: look for '.lo' rather than '.o' object when using Libtool with C++
  cosmetics: few typofixes in older ChangeLogs, suggested by "codespell.py"
  maint: grammar fixes: s/all these/all of these/
  subdir-objects: improve "make mostlyclean" efficiency and flexibility

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

diff --cc automake.in
index ce3cd6e53fed2f778b03c39cfb66f0fa3378cdd4,e5f95ee6499a93c625e03063848984c3be8bde19..7080132b4b498d12adb4f59339a7930a93903a00
--- 1/automake.in
--- 2/automake.in
+++ b/automake.in
@@@ -1860,19 -1950,35 +1860,23 @@@ sub handle_single_transform ($$$$$%
                    err_am "'$full' should not contain a '..' component";
                  }
  
-               # Make sure object is removed by 'make mostlyclean'.
-               $compile_clean_files{$object} = MOSTLY_CLEAN;
-               # If we have a libtool object then we also must remove
-               # the ordinary .o.
-               if ($object =~ /\.lo$/)
-               {
-                   (my $xobj = $object) =~ s,lo$,\$(OBJEXT),;
-                   $compile_clean_files{$xobj} = MOSTLY_CLEAN;
- 
-                   # Remove any libtool object in this directory.
-                   $libtool_clean_directories{$directory} = 1;
-               }
+                 # Make sure *all* objects files in the subdirectory are
+                 # removed by "make mostlyclean".  Not only this is more
+                 # efficient than listing the object files to be removed
+                 # individually (which would cause an 'rm' invocation for
+                 # each of them -- very inefficient, see bug#10697), it
+                 # would also leave stale object files in the subdirectory
+                 # whenever a source file there is removed or renamed.
+                 $compile_clean_files{"$directory/*.\$(OBJEXT)"} = MOSTLY_CLEAN;
+                 if ($object =~ /\.lo$/)
+                   {
+                     # If we have a libtool object, then we also must remove
+                     # any '.lo' objects in its same subdirectory.
+                     $compile_clean_files{"$directory/*.lo"} = MOSTLY_CLEAN;
+                     # Remember to cleanup .libs/ in this directory.
+                     $libtool_clean_directories{$directory} = 1;
+                   }
 -
 -              push (@dep_list, require_build_directory ($directory));
 -
 -              # If we're generating dependencies, we also want
 -              # to make sure that the appropriate subdir of the
 -              # .deps directory is created.
 -              push (@dep_list,
 -                    require_build_directory ($directory . '/$(DEPDIR)'))
 -                unless option 'no-dependencies';
            }
 -
 -          &pretty_print_rule ($object . ':', "\t", @dep_list)
 -              if scalar @dep_list > 0;
        }
  
        # Transform .o or $o file into .P file (for automatic

diff --cc doc/automake-ng.texi
index 563a569eb4fbd58661c16fa64e01449e994a6ea3,02d1bb46cca9d5a18e4d3b8872c96b44d25cfe46..b446fee483794b4cfab976289b395764507afeb7
--- 1/doc/automake-ng.texi
--- 2/doc/automake.texi
+++ b/doc/automake-ng.texi
@@@ -545,16 -538,16 +545,16 @@@ illustration of the GNU Build System i
  @cindex @file{amhello-1.0.tar.gz}, use cases
  
  In this section we explore several use cases for the GNU Build System.
- You can replay all these examples on the @file{amhello-1.0.tar.gz}
+ You can replay all of these examples on the @file{amhello-1.0.tar.gz}
 -package distributed with Automake.  If Automake is installed on your
 -system, you should find a copy of this file in
 +package distributed with Automake-NG.  If Automake-NG is installed on
 +your system, you should find a copy of this file in
  @file{@var{prefix}/share/doc/automake/amhello-1.0.tar.gz}, where
  @var{prefix} is the installation prefix specified during configuration
 -(@var{prefix} defaults to @file{/usr/local}, however if Automake was
 +(@var{prefix} defaults to @file{/usr/local}, however if Automake-NG was
  installed by some GNU/Linux distribution it most likely has been set
 -to @file{/usr}).  If you do not have a copy of Automake installed,
 +to @file{/usr}).  If you do not have a copy of Automake-NG installed,
  you can find a copy of this file inside the @file{doc/} directory of
 -the Automake package.
 +the Automake-NG package.
  
  Some of the following use cases present features that are in fact
  extensions to the GNU Build System.  Read: they are not specified by
@@@ -1572,8 -1565,8 +1572,8 @@@ when you execute @command{make}
  @command{autoreconf} is a script that calls @command{autoconf},
  @command{automake}, and a bunch of other commands in the right order.
  If you are beginning with these tools, it is not important to figure
- out in which order all these tools should be invoked and why.  However,
+ out in which order all of these tools should be invoked and why.  However,
 -because Autoconf and Automake have separate manuals, the important
 +because Autoconf and Automake-NG have separate manuals, the important
  point to understand is that @command{autoconf} is in charge of
  creating @file{configure} from @file{configure.ac}, while
  @command{automake} is in charge of creating @file{Makefile.in}s from

diff --cc lib/am/subdirs.am
Simple merge

diff --cc syntax-checks.mk
Simple merge

diff --cc t/cxx-lt-demo.sh
Simple merge