sysdeps/gnu/configure.ac: handle correctly $libc_cv_rootsbindir

Upstream-Status:Pending
Signed-off-by: Matthieu Crapet <Matthieu.Crapet@ingenico.com>

Index: git/sysdeps/gnu/configure
===================================================================
--- git.orig/sysdeps/gnu/configure	2014-08-27 07:24:38.572070587 +0000
+++ git/sysdeps/gnu/configure	2014-08-27 07:24:41.308070587 +0000
@@ -32,6 +32,6 @@
   else
     libc_cv_localstatedir=$localstatedir
    fi
-  libc_cv_rootsbindir=/sbin
+  test -n "$libc_cv_rootsbindir" || libc_cv_rootsbindir=/sbin
   ;;
 esac
Index: git/sysdeps/gnu/configure.ac
===================================================================
--- git.orig/sysdeps/gnu/configure.ac	2014-08-27 07:24:38.572070587 +0000
+++ git/sysdeps/gnu/configure.ac	2014-08-27 07:24:41.308070587 +0000
@@ -21,6 +21,6 @@
   else
     libc_cv_localstatedir=$localstatedir
    fi
-  libc_cv_rootsbindir=/sbin
+  test -n "$libc_cv_rootsbindir" || libc_cv_rootsbindir=/sbin
   ;;
 esac