- Fix checking for $orbit_config_path in acinclude.m4 (gave an error

   message on STDOUT on AIX and assigned the wrong value)


acinclude.m4:
   - better checking for $orbit_config_path (thanks to Melvyn Sopacua
     for the patch)

acinclude.m4

@@ -800,7 +800,7 @@ dnl get substituted.
 AC_DEFUN(MYSQL_CHECK_ORBIT, [
 AC_MSG_CHECKING(for ORBit)
 orbit_config_path=`which orbit-config`
-if test -n "$orbit_config_path"
+if test -n "$orbit_config_path" -a $? = 0
 then
   orbit_exec_prefix=`orbit-config --exec-prefix`
   orbit_includes=`orbit-config --cflags server`