acinclude: Remove check for 16-bit curl_off_t

Because it's illogical to check for a 16-bit curl_off_t.

Ref: curl#425 (comment)

Author: jay

acinclude.m4

@@ -2837,17 +2837,13 @@ AC_DEFUN([CURL_CONFIGURE_CURL_OFF_T], [
   #
   x_LP64_long=""
   x_LP32_long=""
-  x_LP16_long=""
   #
   if test "$ac_cv_sizeof_long" -eq "8" &&
      test "$ac_cv_sizeof_voidp" -ge "8"; then
     x_LP64_long="long"
   elif test "$ac_cv_sizeof_long" -eq "4" &&
        test "$ac_cv_sizeof_voidp" -ge "4"; then
     x_LP32_long="long"
-  elif test "$ac_cv_sizeof_long" -eq "2" &&
-       test "$ac_cv_sizeof_voidp" -ge "2"; then
-    x_LP16_long="long"
   fi
   #
   dnl DO_CURL_OFF_T_CHECK results are stored in next 3 vars
@@ -2881,17 +2877,6 @@ AC_DEFUN([CURL_CONFIGURE_CURL_OFF_T], [
     done
     AC_MSG_RESULT([$curl_typeof_curl_off_t])
   fi
-  if test "$curl_typeof_curl_off_t" = "unknown"; then
-    AC_MSG_CHECKING([for 16-bit curl_off_t data type])
-    for t2 in          \
-      "$x_LP16_long"   \
-      'int16_t'        \
-      '__int16'        \
-      'int'            ; do
-      DO_CURL_OFF_T_CHECK([$t2], [2])
-    done
-    AC_MSG_RESULT([$curl_typeof_curl_off_t])
-  fi
   if test "$curl_typeof_curl_off_t" = "unknown"; then
     AC_MSG_ERROR([cannot find data type for curl_off_t.])
   fi