configure: don't fail if /usr/include/sys/mount.h does not exist

The AX_CHECK_MOUNT_OPT macro fails if /usr/include/sys/mount.h.
Unfortunately, the GNU HURD doesn't have this header file.  Drop the
requirement, since if it doesn't exist, the macro will assume that
given mount options don't exist, which for e2fsprogs is used to test
to for the existence of the mount options nosuid and nodev.  This is
only used for fuse2fs, and HURD doesn't support fuse2fs anyway.

Addresses-Debian-Bug: #944649
Reported-by: Svante Signell <[email protected]>
Signed-off-by: Theodore Ts'o <[email protected]>

acinclude.m4

@@ -158,10 +158,6 @@ dnl If there was a GNU version, then set @ifGNUmake@ to the empty string, '#' ot
 AC_DEFUN([AX_CHECK_MOUNT_OPT], [__AX_CHECK_MOUNT_OPT(m4_tolower([$1]),m4_toupper([$1]))])
 AC_DEFUN([__AX_CHECK_MOUNT_OPT],
 [
-    AS_IF([test "x$ac_cv_header_sys_mount_h" = x],
-          [AC_CHECK_HEADERS([sys/mount.h])])
-    AS_IF([test "x$ac_cv_header_sys_mount_h" = xno],
-          [AC_MSG_FAILURE([error: sys/mount.h not present on your system!])])
     AS_ECHO_N("checking for mount '$1' option... ")
     AC_TRY_COMPILE(
         [#include <sys/mount.h>],

configure

@@ -13803,26 +13803,6 @@ $as_echo "#define HAVE_EXT2_IOCTLS 1" >>confdefs.h
 	;;
 esac
 
-    if test "x$ac_cv_header_sys_mount_h" = x; then :
-  for ac_header in sys/mount.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "sys/mount.h" "ac_cv_header_sys_mount_h" "$ac_includes_default"
-if test "x$ac_cv_header_sys_mount_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_SYS_MOUNT_H 1
-_ACEOF
-
-fi
-
-done
-
-fi
-    if test "x$ac_cv_header_sys_mount_h" = xno; then :
-  { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
-as_fn_error $? "error: sys/mount.h not present on your system!
-See \`config.log' for more details" "$LINENO" 5; }
-fi
     $as_echo_n "checking for mount 'nosuid' option... "
     cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
@@ -13870,26 +13850,6 @@ fi
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 
 
-    if test "x$ac_cv_header_sys_mount_h" = x; then :
-  for ac_header in sys/mount.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "sys/mount.h" "ac_cv_header_sys_mount_h" "$ac_includes_default"
-if test "x$ac_cv_header_sys_mount_h" = xyes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_SYS_MOUNT_H 1
-_ACEOF
-
-fi
-
-done
-
-fi
-    if test "x$ac_cv_header_sys_mount_h" = xno; then :
-  { { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
-as_fn_error $? "error: sys/mount.h not present on your system!
-See \`config.log' for more details" "$LINENO" 5; }
-fi
     $as_echo_n "checking for mount 'nodev' option... "
     cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */