Fix the configure check so that fair-sched works on Android too.


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13186 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/configure.in b/configure.in
index da0f5d4..78b5339 100644
--- a/configure.in
+++ b/configure.in
@@ -1972,6 +1972,8 @@
 # Verify whether the <linux/futex.h> header is usable.
 AC_MSG_CHECKING([if <linux/futex.h> is usable])
 
+save_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -D__user="
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
 #include <linux/futex.h>
 ]], [[
@@ -1985,6 +1987,8 @@
 ac_have_usable_linux_futex_h=no
 AC_MSG_RESULT([no])
 ])
+CFLAGS="$save_CFLAGS"
+
 
 #----------------------------------------------------------------------------
 # Checks for typedefs, structures, and compiler characteristics.