Merge with gnulib, pacifying GCC 7

This incorporates:
2017-05-16 manywarnings: update for GCC 7
2017-05-15 sys_select: Avoid "was expanded before it was required"
* configure.ac (nw): Suppress GCC 7’s new -Wduplicated-branches and
-Wformat-overflow=2 options, due to too many false alarms.
* doc/misc/texinfo.tex, lib/strftime.c, m4/manywarnings.m4:
Copy from gnulib.
* m4/gnulib-comp.m4: Regenerate.
* src/coding.c (decode_coding_iso_2022):
Fix bug uncovered by -Wimplicit-fallthrough.
* src/conf_post.h (FALLTHROUGH): New macro.
Use it to mark all switch cases that fall through.
* src/editfns.c (styled_format): Use !, not ~, on bool.
* src/gtkutil.c (xg_check_special_colors):
When using sprintf, don’t trust Gtk to output colors in [0, 1] range.
(xg_update_scrollbar_pos): Avoid use of possibly-uninitialized bool;
this bug was actually caught by Clang.
* src/search.c (boyer_moore):
Tell GCC that CHAR_BASE, if nonzero, must be a non-ASCII character.
* src/xterm.c (x_draw_glyphless_glyph_string_foreground):
Tell GCC that glyph->u.glyphless.ch must be a character.

1 files changed, 5 insertions, 5 deletions

diff --git a/src/editfns.c b/src/editfns.c
index 38530437a2f..ecb8e3f0838 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -1595,10 +1595,10 @@ time_arith (Lisp_Object a, Lisp_Object b,
     {
     default:
       val = Fcons (make_number (t.ps), val);
-      /* Fall through.  */
+      FALLTHROUGH;
     case 3:
       val = Fcons (make_number (t.us), val);
-      /* Fall through.  */
+      FALLTHROUGH;
     case 2:
       val = Fcons (make_number (t.lo), val);
       val = Fcons (make_number (t.hi), val);
@@ -4072,8 +4072,8 @@ styled_format (ptrdiff_t nargs, Lisp_Object *args, bool message)
             }
 
           /* Ignore flags when sprintf ignores them.  */
-          space_flag &= ~ plus_flag;
-          zero_flag &= ~ minus_flag;
+          space_flag &= ! plus_flag;
+          zero_flag &= ! minus_flag;
 
           char *num_end;
           uintmax_t raw_field_width = strtoumax (format, &num_end, 10);
@@ -4311,7 +4311,7 @@ styled_format (ptrdiff_t nargs, Lisp_Object *args, bool message)
                   {
                     memcpy (f, pMd, pMlen);
                     f += pMlen;
-                    zero_flag &= ~ precision_given;
+                    zero_flag &= ! precision_given;
                   }
                 *f++ = conversion;
                 *f = '\0';