[glib] Don't enable dtrace support when dtrace isn't available

[Ryan Lortie <ryanl src gnome org>]

commit dd9f8b8cc6d873517dedd83935ed0d994bbbd6c9
Author: Emilio Pozuelo Monfort <pochu27 gmail com>
Date:   Tue Sep 28 11:53:03 2010 +0200

    Don't enable dtrace support when dtrace isn't available
    
    Fixes FTBFS when dtrace isn't available but <sys/sdt.h> is.

 configure.ac |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index c6fc9a1..51591d8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2787,11 +2787,12 @@ if test "x$enable_dtrace" != xno; then
       if test "x$enable_dtrace" = xyes; then
         AC_MSG_ERROR([dtrace not found])
       fi
+    else
+      AC_CHECK_HEADER([sys/sdt.h],have_dtrace=yes,
+                      [if test "x$enable_dtrace" = xyes; then
+                        AC_MSG_ERROR([dtrace support needs sys/sdt.h header])
+                       fi])
     fi
-    AC_CHECK_HEADER([sys/sdt.h],have_dtrace=yes,
-                    [if test "x$enable_dtrace" = xyes; then
-                      AC_MSG_ERROR([dtrace support needs sys/sdt.h header])
-                     fi])
   fi
 else
   AC_MSG_RESULT([no])