Merge branch 'master' into ng/master

* master:
  tests: avoid a spurious failure when $CC != cc
  NEWS: drop an idiomatic use of latinism 'sic'
  NEWS: fix typos and grammaros
  NEWS: fix Automake versions
  NEWS: document fix for bug#14441
  Automake::Rule: consistently prepend underscore to private variables
  Automake::Rule: rename: suffix_rule() -> next_in_suffix_chain()
  Automake::Rule: adjust comments and POD according to previous changes
  Automake::Rule: make private variables lexically scoped
  suffix rules: better distinction between builtin and user-derived
  Automake::Rule: expose suffix rules as a function, not a scalar
  tests: expose automake bug#14441

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
+ Extra non-trivial changes:

* bin/automake.in, lib/Automake/Rule.pm: Drop changes related to
user-defined source extensions, that are not supported in Automake-NG
(see section "Source Files with Unknown Extensions" in NG-NEWS for
details).
t/suffix-custom-pr14441.sh: Remove, since this script tested features
related to user-defined source.

diff --cc lib/Automake/Rule.pm
index 286dfbaf2e76c86ec90c514ad54a1232ccbb780e,ac4b71afd216e961ca5eb24e9bc768110fc0f2a6..c5048a729b07bc90ecc4e3e6fd5dfe838933e39d
--- 1/lib/Automake/Rule.pm
--- 2/lib/Automake/Rule.pm
+++ b/lib/Automake/Rule.pm
@@@ -93,6 -96,21 +93,8 @@@ non-object)
  
  =cut
  
 -my $_SUFFIX_RULE_PATTERN =
 -  '^(\.[a-zA-Z0-9_(){}$+@\-]+)(\.[a-zA-Z0-9_(){}$+@\-]+)' . "\$";
 -
 -my @_suffixes = ();
 -my @_known_extensions_list = ();
 -my %_rule_dict = ();
 -
 -# See comments in the implementation of the 'next_in_suffix_chain()'
 -# variable for details.
 -my %_suffix_rules;
 -
 -# Same as $suffix_rules, but records only the default rules
 -# supplied by the languages Automake supports.
 -my %_suffix_rules_builtin;
++my %_rule_dict;
+ 
  =item C<%dependencies>
  
  Holds the dependencies of targets which dependencies are factored.

diff --cc t/subpkg.sh
Simple merge