Fix typo

include/ffi.h.in

@@ -1,5 +1,5 @@
 /* -----------------------------------------------------------------*-C-*-
-   libffi @VERSION@ - Copyright (c) 2011 Anthony Green
+   libffi @VERSION@ - Copyright (c) 2011, 2014 Anthony Green
                     - Copyright (c) 1996-2003, 2007, 2008 Red Hat, Inc.
 
    Permission is hereby granted, free of charge, to any person
@@ -221,10 +221,10 @@ typedef struct {
 #endif
 } ffi_cif;
 
-#if HAVE_LONG_DOUBLE_VARIANT
+#if @HAVE_LONG_DOUBLE_VARIANT@
 /* Used to adjust size/alignment of ffi types.  */
 void ffi_prep_types (ffi_abi abi);
-# endif
+#endif
 
 /* Used internally, but overridden by some architectures */
 ffi_status ffi_prep_cif_core(ffi_cif *cif,