Removed gcc debug stl because it is too easy to shoot yourself in the foot with.

environment.py

@@ -558,7 +558,7 @@ class GnuCPPCompiler(CPPCompiler):
     std_warn_flags = ['-Wall', '-Winvalid-pch']
     std_opt_flags = ['-O2']
     # may need to separate the latter to extra_debug_flags or something
-    std_debug_flags = ['-g', '-D_GLIBCXX_DEBUG']
+    std_debug_flags = ['-g']
 
     def __init__(self, exelist, version, is_cross, exe_wrap):
         CPPCompiler.__init__(self, exelist, version, is_cross, exe_wrap)