Omit a few minor unnecessary range checks

Based on Pip Cet’s review (Bug#36370#19).
* src/fileio.c (Fdo_auto_save):
* src/image.c (lookup_image):
* src/textprop.c (Fnext_single_char_property_change):
Prefer XFIXNUM to XFIXNAT for clarity and consistency with
neighboring code, and to avoid unnecessary range checks.
* src/image.c (lookup_image): Omit unnecessary range checks.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/textprop.c b/src/textprop.c
index 3026ec7e992..9023f4efa06 100644
--- a/src/textprop.c
+++ b/src/textprop.c
@@ -799,10 +799,10 @@ last valid position in OBJECT.  */)
       else
         CHECK_FIXNUM_COERCE_MARKER (limit);
 
-      if (XFIXNAT (position) >= XFIXNUM (limit))
+      if (XFIXNUM (position) >= XFIXNUM (limit))
         {
           position = limit;
-          if (XFIXNAT (position) > ZV)
+          if (XFIXNUM (position) > ZV)
             XSETFASTINT (position, ZV);
         }
       else