configure.ac: remove unused AC_INCLUDEDIR

* configure.ac (AC_INCLUDEDIR): Remove.
* m4/includedir.m4: Remove.

configure.ac

@@ -144,8 +144,6 @@ AC_MSG_RESULT($arch)
 
 AC_SUBST(arch)
 
-AC_INCLUDEDIR
-
 AC_ARG_ENABLE([arm-oabi],
 	      [AS_HELP_STRING([--enable-arm-oabi],
 			      [enable OABI support on ARM EABI])],

m4/includedir.m4

@@ -1,23 +0,0 @@
-dnl ### A macro to find the include directory, useful for cross-compiling.
-AC_DEFUN([AC_INCLUDEDIR],
-[AC_REQUIRE([AC_PROG_AWK])dnl
-AC_SUBST(includedir)
-AC_MSG_CHECKING(for primary include directory)
-includedir=/usr/include
-if test -n "$GCC"
-then
-	>conftest.c
-	new_includedir=`
-		$CC -v -E conftest.c 2>&1 | $AWK '
-			/^End of search list/ { print last; exit }
-			{ last = [$]1 }
-		'
-	`
-	rm -f conftest.c
-	if test -n "$new_includedir" && test -d "$new_includedir"
-	then
-		includedir=$new_includedir
-	fi
-fi
-AC_MSG_RESULT($includedir)
-])