Remove configure's check for nonstandard "long long" printf modifiers.

We used to claim to support platforms using 'q' or 'I64' as the printf
length modifier for long long int, by dint of replacing snprintf with
our own code which uses the C99 standard 'll' modifier.  But that is
only adequate if we use INT64_MODIFIER only in snprintf-based calls,
not directly with the platform's native printf or fprintf.  Which
hasn't been the case for years.  We had not noticed, partially because
of inadequate test coverage, and partially because the buildfarm is
almost completely bare of machines that won't take 'll'.  The last
one seems to have been frogmouth, which was adjusted recently so that
it will take 'll'.  We might as well just give up on the pretense
that anything else works, and save ourselves some configure cycles.

Discussion: https://postgr.es/m/13103.1526749980@sss.pgh.pa.us
Discussion: https://postgr.es/m/24769.1526772680@sss.pgh.pa.us

configure.in

@@ -1601,7 +1601,7 @@ if test "$PORTNAME" = "win32"; then
   #   strings, replacements are provided through <libintl.h>.
   #
   # We could use libintl >= 0.13's *printf() if we were sure that we had
-  # a litint >= 0.13 at runtime, but seeing that there is no clean way
+  # a libintl >= 0.13 at runtime, but seeing that there is no clean way
   # to guarantee that, it is best to just use our own, so we are sure to
   # get %$ support. In include/port.h we disable the *printf() macros
   # that might have been defined by libintl.
@@ -1804,20 +1804,9 @@ fi
 
 
 dnl Check to see if we have a working 64-bit integer type.
-dnl This breaks down into two steps:
-dnl (1) figure out if the compiler has a 64-bit int type with working
-dnl arithmetic, and if so
-dnl (2) see whether snprintf() can format the type correctly.  (Currently,
-dnl snprintf is the only library routine we really need for int8 support.)
-dnl It's entirely possible to have a compiler that handles a 64-bit type
-dnl when the C library doesn't; this is fairly likely when using gcc on
-dnl an older platform, for example.
-dnl If there is no native snprintf() or it does not handle the 64-bit type,
-dnl we force our own version of snprintf() to be used instead.
-dnl Note this test must be run after our initial check for snprintf/vsnprintf.
-
-dnl As of Postgres 8.4, we no longer support compilers without a working
-dnl 64-bit type.  But we still handle the case of snprintf being broken.
+dnl Since Postgres 8.4, we no longer support compilers without a working
+dnl 64-bit type; but we have to determine whether that type is called
+dnl "long int" or "long long int".
 
 PGAC_TYPE_64BIT_INT([long int])
 
@@ -1835,34 +1824,20 @@ fi
 AC_DEFINE_UNQUOTED(PG_INT64_TYPE, $pg_int64_type,
   [Define to the name of a signed 64-bit integer type.])
 
-# If we found "long int" is 64 bits, assume snprintf handles it.  If
-# we found we need to use "long long int", better check.  We cope with
-# snprintfs that use %lld, %qd, or %I64d as the format.  If none of these
-# work, fall back to our own snprintf emulation (which we know uses %lld).
-
-if test "$HAVE_LONG_LONG_INT_64" = yes ; then
-  if test $pgac_need_repl_snprintf = no; then
-    PGAC_FUNC_SNPRINTF_LONG_LONG_INT_MODIFIER
-    if test "$LONG_LONG_INT_MODIFIER" = ""; then
-      # Force usage of our own snprintf, since system snprintf is broken
-      pgac_need_repl_snprintf=yes
-      LONG_LONG_INT_MODIFIER='ll'
-    fi
-  else
-    # Here if we previously decided we needed to use our own snprintf
-    LONG_LONG_INT_MODIFIER='ll'
-  fi
+# Select the printf length modifier that goes with that, too.
+# (This used to be bound up with replacement-snprintf selection, but now
+# we assume that the native *printf functions use standard length modifiers.)
+if test x"$pg_int64_type" = x"long long int" ; then
+  INT64_MODIFIER='"ll"'
 else
-  # Here if we are not using 'long long int' at all
-  LONG_LONG_INT_MODIFIER='l'
+  INT64_MODIFIER='"l"'
 fi
 
-INT64_MODIFIER="\"$LONG_LONG_INT_MODIFIER\""
-
 AC_DEFINE_UNQUOTED(INT64_MODIFIER, $INT64_MODIFIER,
-                   [Define to the appropriate snprintf length modifier for 64-bit ints.])
+                   [Define to the appropriate printf length modifier for 64-bit ints.])
 
-# Also force use of our snprintf if the system's doesn't support the %z flag.
+# Force use of our snprintf if the system's doesn't support the %z flag.
+# (Note this test uses PG_INT64_TYPE and INT64_MODIFIER.)
 if test "$pgac_need_repl_snprintf" = no; then
   PGAC_FUNC_SNPRINTF_SIZE_T_SUPPORT
   if test "$pgac_cv_snprintf_size_t_support" != yes; then