Bug#882531: xorg-server FTCBFS: assumes CLOCK_MONOTONIC to be unavailable

[Helmut Grohne <helmut@subdivi.de>]

Source: xorg-server
Version: 2:1.19.5-1
Tags: patch upstream
User: helmutg@debian.org
Usertags: rebootstrap

xorg-server fails to cross build from source, because its configure
checks for CLOCK_MONOTONIC with AC_RUN_IFELSE and then figures that for
cross compilation CLOCK_MONOTONIC likely is not available. It then gives
up, because wayland requires CLOCK_MONOTONIC. I think this is a bad
default as it always breaks cross compilation. I propose resorting to a
weaker assumption for cross compilation where only the presence of the
CLOCK_MONOTONIC declaration is checked and it is assumed working. Since
wayland requires CLOCK_MONOTONIC anyway, the check really is only a
sanity check. After fixing this, xorg-server cross builds successfully.
Please consider applying the attached patch.

Helmut

Index: xorg-server-1.19.5/configure.ac
===================================================================
--- xorg-server-1.19.5.orig/configure.ac
+++ xorg-server-1.19.5/configure.ac
@@ -1073,6 +1073,9 @@
 fi
 
 AC_MSG_RESULT([$MONOTONIC_CLOCK])
+if test "$MONOTONIC_CLOCK" = "cross compiling"; then
+    AC_CHECK_DECL([CLOCK_MONOTONIC],[MONOTONIC_CLOCK=yes],[MONOTONIC_CLOCK=no],[#include <time.h>])
+fi
 
 if test "x$MONOTONIC_CLOCK" = xyes; then
     AC_DEFINE(MONOTONIC_CLOCK, 1, [Have monotonic clock from clock_gettime()])