maint: assume long long int

It’s long been safe to assume C99+ support for long long int.
* .gitignore: Remove m4/longlong.m4.
* bootstrap.conf (buildreq): Boost git prereq from 1.4.4 to 1.5.5,
syncing with Gnulib.
(bootstrap_post_import_hook): Remove m4/longlong.m4.
* m4/jm-macros.m4 (gl_CHECK_ALL_TYPES):
No need to require AC_TYPE_UNSIGNED_LONG_LONG_INT.
* src/factor.c (DItype, UDItype):
* src/od.c (main):
Assume HAVE_LONG_LONG_INT.
* src/od.c: (unsigned_long_long_int):
Remove.  All uses replaced with unsigned long long int.

bootstrap.conf

@@ -1,4 +1,4 @@
-# Bootstrap configuration.
+# Bootstrap configuration.                                          -*- sh -*-
 
 # Copyright (C) 2006-2025 Free Software Foundation, Inc.
 
@@ -340,7 +340,7 @@ XGETTEXT_OPTIONS=$XGETTEXT_OPTIONS'\\\
  --from-code=UTF-8\\\
 '
 
-# Append these, since we use the propername module.
+# Append these, since we use the propername-lite module.
 see_manual='"This is a proper name. See the gettext manual, section Names."'
 see_manual=\'"$see_manual"\'
 XGETTEXT_OPTIONS=$XGETTEXT_OPTIONS'\\\
@@ -359,7 +359,7 @@ automake   1.11.2
 autopoint  0.19.2
 bison      -
 gettext    0.19.2
-git        1.4.4
+git        1.5.5
 gperf      -
 gzip       -
 m4         -
@@ -385,6 +385,13 @@ bootstrap_post_import_hook ()
     && chmod a-w $tmp-1 $tmp-2 \
     && mv -f $tmp-1 $m4f && mv -f $tmp-2 $mkf)
 
+  # If "AM_GNU_GETTEXT(external" or "AM_GNU_GETTEXT([external]" appears
+  # in configure.ac, remove a file unnecessarily imported by autopoint.
+  if grep '^[	 ]*AM_GNU_GETTEXT(\[*external]*[,)]' \
+          configure.ac >/dev/null 2>&1; then
+    rm -f m4/longlong.m4
+  fi
+
   # Regenerate src/single-binary.mk
   (mkf=src/single-binary.mk tmp=single-binary.tmp \
     && rm -f $mkf $tmp \