maint: clean up the output from syntax-check rules

* cfg.mk (sc_tight_scope): Pass the -s (silent) flag to `make`
so that it doesn't report about calling sub makes.
(sc_check-AUTHORS): Likewise.
(sc_strftime_check): Don't display stderr from `info`.
* src/Makefile.am (sc_tight_scope): Don't annotate with "GEN".
(sc_check-AUTHORS): Likewise.

cfg.mk

@@ -165,11 +165,11 @@ sc_sun_os_names:
 
 ALL_RECURSIVE_TARGETS += sc_tight_scope
 sc_tight_scope:
-	@$(MAKE) -C src $@
+	@$(MAKE) -s -C src $@
 
 ALL_RECURSIVE_TARGETS += sc_check-AUTHORS
 sc_check-AUTHORS:
-	@$(MAKE) -C src $@
+	@$(MAKE) -s -C src $@
 
 # Option descriptions should not start with a capital letter
 # One could grep source directly as follows:
@@ -218,7 +218,7 @@ sc_strftime_check:
 	  grep '^  %.  ' $(srcdir)/src/date.c | sort			\
 	    | $(extract_char) > $@-src;					\
 	  { echo N;							\
-	    info libc date calendar format | grep '^    `%.'\'		\
+	    info libc date calendar format 2>/dev/null|grep '^    `%.'\'\
 	      | $(extract_char); } | sort > $@-info;			\
 	  diff -u $@-src $@-info || exit 1;				\
 	  rm -f $@-src $@-info;						\

src/Makefile.am

@@ -678,7 +678,7 @@ au_dotdot = authors-dotdot
 au_actual = authors-actual
 .PHONY: sc_check-AUTHORS
 sc_check-AUTHORS: $(all_programs)
-	$(AM_V_GEN)locale=en_US.UTF-8;			\
+	@locale=en_US.UTF-8;				\
 	LC_ALL="$$locale" ./cat --version		\
 	    | grep ' Torbjorn '	> /dev/null		\
 	  && { echo "$@: skipping this check"; exit 0; }; \
@@ -714,7 +714,7 @@ sc_check-AUTHORS: $(all_programs)
 # The second nm|grep checks for file-scope variables with `extern' scope.
 .PHONY: sc_tight_scope
 sc_tight_scope: $(bin_PROGRAMS)
-	$(AM_V_GEN)t=exceptions-$$$$;					\
+	@t=exceptions-$$$$;						\
 	trap "s=$$?; rm -f $$t; exit $$s" 0 1 2 13 15;			\
 	src=`for f in $(SOURCES); do					\
 	       test -f $$f && d= || d=$(srcdir)/; echo $$d$$f; done`;	\