Fix endian handling w.r.t. CPP macro WORDS_BIGENDIAN

Include header file `ghcautoconf.h` where the CPP macro
`WORDS_BIGENDIAN` is defined. This finally fixes #17337 (in conjunction
with commit 6c59cc71).

(cherry picked from commit 3c12355e)
(cherry picked from commit 11f8eef5)

libraries/base/GHC/ByteOrder.hs

@@ -17,6 +17,9 @@
 
 module GHC.ByteOrder where
 
+-- Required for WORDS_BIGENDIAN
+#include <ghcautoconf.h>
+
 -- | Byte ordering.
 data ByteOrder
     = BigEndian    -- ^ most-significant-byte occurs in lowest address.

libraries/base/GHC/IO/Encoding/CodePage/API.hs

@@ -7,6 +7,9 @@ module GHC.IO.Encoding.CodePage.API (
     mkCodePageEncoding
   ) where
 
+-- Required for WORDS_BIGENDIAN
+#include <ghcautoconf.h>
+
 import Foreign.C
 import Foreign.Ptr
 import Foreign.Marshal

testsuite/tests/codeGen/should_run/T7600.hs

+{-# LANGUAGE CPP #-}
 -- !!! Bug # 7600.
 -- The LLVM backend can be tricky to get right with floating point constants
 -- and GHC. See Note [LLVM Float Types] in compiler/llvmGen/Llvm/Types.hs for
@@ -16,6 +17,9 @@
 -- Also worth looking at ticket # 3676 about issues with 'realToFrac'.
 module Main (main) where
 
+-- Required for WORDS_BIGENDIAN
+#include <ghcautoconf.h>
+
 import T7600_A
 
 -- a fp constant that requires double precision, but we only use a single