[PATCH 1 of 5] blktap: remove HAVE_BYTESWAP_H checking, since it's defined by qemu

[Roger Pau Monne <roger.pau@entel.upc.edu>]

# HG changeset patch
# User Roger Pau Monne <roger.pau@entel.upc.edu>
# Date 1324171782 -3600
# Node ID eed78eb655c40b0ac9af1b14c1cc03204f696b0b
# Parent  b783e76e63a99c9d87fca4974492f60af99a2e7a
blktap: remove HAVE_BYTESWAP_H checking, since it's defined by qemu

blktap was using defines set by qemu, even when the qemu config file
is not included. Remove this checkings, and instead check if the file
has been included before defining the necessary macros.

The output error is:

In file included from block-qcow.c:37:0:
bswap.h:23:0: error: "bswap_16" redefined [-Werror]
/usr/include/byteswap.h:30:0: note: this is the location of the
previous definition
bswap.h:31:0: error: "bswap_32" redefined [-Werror]
/usr/include/byteswap.h:33:0: note: this is the location of the
previous definition
bswap.h:41:0: error: "bswap_64" redefined [-Werror]
/usr/include/byteswap.h:37:0: note: this is the location of the
previous definition
cc1: all warnings being treated as errors

Signed-off-by: Roger Pau Monne <roger.pau@entel.upc.edu>

diff -r b783e76e63a9 -r eed78eb655c4 tools/blktap/drivers/bswap.h
--- a/tools/blktap/drivers/bswap.h	Sun Dec 18 02:29:42 2011 +0100
+++ b/tools/blktap/drivers/bswap.h	Sun Dec 18 02:29:42 2011 +0100
@@ -15,9 +15,7 @@
 #define bswap_64(x) swap64(x)
 #else
 
-#ifdef HAVE_BYTESWAP_H
-#include <byteswap.h>
-#else
+#ifndef _BYTESWAP_H
 
 #define bswap_16(x) \
 ({ \
@@ -51,7 +49,7 @@
 		(uint64_t)(((uint64_t)(__x) & (uint64_t)0xff00000000000000ULL) >> 56) )); \
 })
 
-#endif /* !HAVE_BYTESWAP_H */
+#endif /* !_BYTESWAP_H */
 
 static inline uint16_t bswap16(uint16_t x)
 {