tests: Run processes under test with G_DEBUG=fatal-warnings

Modify all the similar Python test wrappers to set
`G_DEBUG=fatal-warnings` in the environment of the program being tested,
so we can catch unexpected warnings/criticals.

Adding this because I noticed it was missing, not because I noticed a
warning/critical was being ignored.

Signed-off-by: Philip Withnall <philip@tecnocode.co.uk>

gobject/tests/genmarshal.py

@@ -88,6 +88,7 @@ class TestGenmarshal(unittest.TestCase):
 
         env = os.environ.copy()
         env["LC_ALL"] = "C.UTF-8"
+        env["G_DEBUG"] = "fatal-warnings"
         print("Environment:", env)
 
         # We want to ensure consistent line endings...

gobject/tests/gobject-query.py

@@ -59,6 +59,7 @@ class TestGobjectQuery(unittest.TestCase):
 
         env = os.environ.copy()
         env["LC_ALL"] = "C.UTF-8"
+        env["G_DEBUG"] = "fatal-warnings"
         print("Environment:", env)
 
         # We want to ensure consistent line endings...

gobject/tests/mkenums.py

@@ -100,6 +100,7 @@ class TestMkenums(unittest.TestCase):
 
         env = os.environ.copy()
         env["LC_ALL"] = "C.UTF-8"
+        env["G_DEBUG"] = "fatal-warnings"
         print("Environment:", env)
 
         # We want to ensure consistent line endings...