wendelin: custom test runner to load our own libstdc++

Now the test runners use the LD_PRELOAD environment variable to load
the correct libstdc++ built by slapos and restart themselves.

The restart is necesasry because LD_PRELOAD is only taken into account
at the time the process is started. Changing this environment variable
in runtime has no effects.

software/wendelin/software.cfg

@@ -12,6 +12,8 @@ parts +=
   ipython
   wendelin.core
   ipython-notebook
+  wendelin_test_suite_runner
+  wendelin_testrunner
 
 [eggs]
 initialization =
@@ -24,7 +26,35 @@ eggs +=
   ${msgpack-python:egg}
   ${wendelin.core:egg}
   ${ipython:egg}
-
+  
+[generic_testrunner_init]
+initialization = 
+  # The 4 lines below will replace the process with another one, with the proper
+  # LD_PRELOAD environment variable. This is necessary because LD_PRELOAD is only
+  # taken into account when the process starts. Modifying it in runtime doesn't
+  # work.
+  import struct, os
+  arch = 8 * struct.calcsize("P")
+  rerun = not os.getenv('LD_PRELOAD')
+  if rerun: os.environ['LD_PRELOAD'] = '''${gcc-fortran:location}/lib%s/libstdc++.so''' % arch
+  if rerun: os.execve(os.path.realpath(__file__), sys.argv, os.environ)
+  
+[wendelin_test_suite_runner]
+<= test_suite_runner
+# we need to override the test suite runner to add our custom libstdc++ dynamic
+# library to the path
+initialization =
+  ${generic_testrunner_init:initialization}
+  ${test_suite_runner:initialization}
+  
+[wendelin_testrunner]
+<= testrunner
+# we need to override the test suite runner to add our custom libstdc++ dynamic
+# library to the path
+initialization =
+  ${generic_testrunner_init:initialization}
+  ${testrunner:initialization}
+ 
 [erp5_repository_list]
 repository_id_list += wendelin