direct stderr output to stderr again

[wjwwood]

Replacement for #400, as I could not push to that pr.

[wjwwood]

Starting with a baseline output of:

% catkin b
==> Expanding alias 'b' from 'catkin b' to 'catkin build'
-------------------------------------------------------------------
Profile:                     default
Extending:                   None
Workspace:                   /Users/william/Desktop/test_ws
-------------------------------------------------------------------
Source Space:       [exists] /Users/william/Desktop/test_ws/src
Log Space:          [exists] /Users/william/Desktop/test_ws/logs
Build Space:        [exists] /Users/william/Desktop/test_ws/build
Devel Space:        [exists] /Users/william/Desktop/test_ws/devel
Install Space:      [exists] /Users/william/Desktop/test_ws/install
DESTDIR:            [unused] None
-------------------------------------------------------------------
Devel Space Layout:          linked
Install Space Layout:        merged
-------------------------------------------------------------------
Additional CMake Args:       None
Additional Make Args:        None
Additional catkin Make Args: None
Internal Make Job Server:    True
Cache Job Environments:      False
-------------------------------------------------------------------
Whitelisted Packages:        None
Blacklisted Packages:        None
-------------------------------------------------------------------


-------------------------------------------------------------------
WARNING: Your workspace is not extending any other result space,
but it is set to use a `linked` devel space layout. This requires
the `catkin` CMake package in your source space in order to be
built.
-------------------------------------------------------------------

[build] Found '2' packages in 0.0 seconds.
Starting  >>> catkin
Finished  <<< catkin                [ 0.2 seconds ]
Starting  >>> serial
_________________________________________________________________________________________________________________________________________________________________________________
Errors     << serial:make /Users/william/Desktop/test_ws/logs/serial/build.make.015.log
/Users/william/Desktop/test_ws/src/serial/src/impl/unix.cc:85:8: error: no member named 'bar' in 'timespec'
  time.bar = 2;
  ~~~~ ^
1 error generated.
make[2]: *** [CMakeFiles/serial.dir/src/impl/unix.cc.o] Error 1
make[1]: *** [CMakeFiles/serial.dir/all] Error 2
make: *** [all] Error 2
cd /Users/william/Desktop/test_ws/build/serial; catkin build --get-env serial | catkin env -si  /usr/bin/make --jobserver-fds=6,7 -j; cd -
.................................................................................................................................................................................
Failed     << serial:make           [ Exited with code 2 ]
Failed    <<< serial                [ 0.6 seconds ]
[build] Summary: 1 of 2 packages succeeded.
[build]   Ignored:   None.
[build]   Warnings:  None.
[build]   Abandoned: None.
[build]   Failed:    1 packages failed.
[build] Runtime: 1.1 seconds total.

Without this patch, redirecting stdout to /dev/null looked like this:

% catkin b > /dev/null

With this patch, it works like this:

% catkin b > /dev/null
_________________________________________________________________________________________________________________________________________________________________________________
Errors << serial:make /Users/william/Desktop/test_ws/logs/serial/build.make.016.log
/Users/william/Desktop/test_ws/src/serial/src/impl/unix.cc:85:8: error: no member named 'bar' in 'timespec'
  time.bar = 2;
  ~~~~ ^
1 error generated.
make[2]: *** [CMakeFiles/serial.dir/src/impl/unix.cc.o] Error 1
make[1]: *** [CMakeFiles/serial.dir/all] Error 2
make: *** [all] Error 2
cd /Users/william/Desktop/test_ws/build/serial; catkin build --get-env serial | catkin env -si  /usr/bin/make --jobserver-fds=6,7 -j; cd -
.................................................................................................................................................................................
Failed << serial:make            [ Exited with code 2 ]

[wjwwood]

Switching to a warning in the test package also works:

% catkin b > /dev/null
_________________________________________________________________________________________________________________________________________________________________________________
Warnings << serial:make /Users/william/Desktop/test_ws/logs/serial/build.make.017.log
/Users/william/Desktop/test_ws/src/serial/src/impl/unix.cc:86:13: warning: implicit conversion from 'float' to 'int' changes value from 1.3 to 1 [-Wliteral-conversion]
  int foo = 1.3f;
      ~~~   ^~~~
1 warning generated.
cd /Users/william/Desktop/test_ws/build/serial; catkin build --get-env serial | catkin env -si  /usr/bin/make --jobserver-fds=6,7 -j; cd -
.................................................................................................................................................................................

[wjwwood]

Thanks again @rhaschke.