[PATCH ethtool 1/2] configure.ac: Remove feature test for <sys/ioctl.h>

<sys/ioctl.h> has been a hard dependency for as back as git history
goes (2005, shortly after version 3).

Signed-off-by: Ben Hutchings <redacted>
---
I spotted this while reviewing David Decotigny's patch to use netlink
sockets.

Ben.

 configure.ac | 1 -
 1 file changed, 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 3105415be026..6ebffedc9f5b 100644
--- a/configure.ac
+++ b/configure.ac

@@ -15,7 +15,6 @@ AM_PROG_CC_C_O
 dnl Checks for libraries.
 
 dnl Checks for header files.
-AC_CHECK_HEADERS(sys/ioctl.h)
 
 dnl Checks for typedefs, structures, and compiler characteristics.
 AC_MSG_CHECKING([whether <linux/types.h> defines big-endian types])