Fix for alex-3.5.2.0 (#25623)

This INLINE pragma for alexScanUser was added in 9.12, but then I
ported the change to alex in 3.5.2.0
(https://github.com/haskell/alex/pull/262).

I didn't realize that GHC errors on duplicate INLINE pragmas, so
this ended up being a breaking change.

This change should be backported into 9.12

(cherry picked from commit a1d92378)

compiler/GHC/Parser/Lexer.x

@@ -41,6 +41,7 @@
 -- Alex "Haskell code fragment top"
 
 {
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE ViewPatterns #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE MultiWayIf #-}
@@ -3471,10 +3472,14 @@ topNoLayoutContainsCommas [] = False
 topNoLayoutContainsCommas (ALRLayout _ _ : ls) = topNoLayoutContainsCommas ls
 topNoLayoutContainsCommas (ALRNoLayout b _ : _) = b
 
+#ifdef MIN_TOOL_VERSION_alex
+#if !MIN_TOOL_VERSION_alex(3,5,2)
 -- If the generated alexScan/alexScanUser functions are called multiple times
 -- in this file, alexScanUser gets broken out into a separate function and
 -- increases memory usage. Make sure GHC inlines this function and optimizes it.
 {-# INLINE alexScanUser #-}
+#endif
+#endif
 
 lexToken :: P (PsLocated Token)
 lexToken = do