build: downgrade maybe-uninitialized from an error to a warning

maybe-uninitialized has false positives in gcc 4.8 due to Boost ticket #9134 https://svn.boost.org/trac/boost/ticket/9134

refs #1615

Change-Id: I0dc1597211a21f1b489ba9c4e10ee787aa49207c
diff --git a/.waf-tools/default-compiler-flags.py b/.waf-tools/default-compiler-flags.py
index 7e818ea..0ffaa9d 100644
--- a/.waf-tools/default-compiler-flags.py
+++ b/.waf-tools/default-compiler-flags.py
@@ -28,6 +28,7 @@
                          '-fdiagnostics-color', # gcc >= 4.9
                          '-Werror',
                          '-Wno-error=deprecated-register',
+                         '-Wno-error=maybe-uninitialized', # Bug #1615
                         ]
         if areCustomCxxflagsPresent:
             missingFlags = [x for x in defaultFlags if x not in conf.env.CXXFLAGS]