sdl12-compat: cleanup to RWops12to20_size():

SDL Commits
1 
From 008851021472f305e9831914240928e0e4276311 Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Mon, 1 Mar 2021 14:10:50 +0300
Subject: [PATCH] cleanup to RWops12to20_size():

only care about first SEEK_CUR seek error (and set SDL_EFSEEK for it),
and remove other error checks.
---
 src/SDL12_compat.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/src/SDL12_compat.c b/src/SDL12_compat.c
index 79238dc..4f1772c 100644
--- a/src/SDL12_compat.c
+++ b/src/SDL12_compat.c
@@ -4347,14 +4347,11 @@ RWops12to20_size(struct SDL_RWops *rwops20)
         return size;
 
     pos = rwops12->seek(rwops12, 0, RW_SEEK_CUR);
-    if (pos == -1)
-        return -1;
-
+    if (pos == -1) {
+        return SDL20_Error(SDL_EFSEEK);
+    }
     size = (Sint64) rwops12->seek(rwops12, 0, RW_SEEK_END);
-    if (size == -1)
-        return -1;
-
-    rwops12->seek(rwops12, pos, RW_SEEK_SET);  FIXME("...and if this fails?");
+    rwops12->seek(rwops12, pos, RW_SEEK_SET);
     rwops20->hidden.unknown.data2 = (void *) ((size_t) size);
     return size;
 }