Fix maybe-uninitialized warnings from GCC 4.8.x

Fixes the following warnings in `p=server target=release_debug` builds
on Travis CI:
```
./core/os/memory.h: In function 'MainLoop* TestOAHashMap::test()':
./core/os/memory.h:108:111: warning: 'dummy' may be used uninitialized in this function [-Wmaybe-uninitialized]
 #define memnew_placement(m_placement, m_class) _post_initialize(new (m_placement, sizeof(m_class), "") m_class)
                                                                                                               ^
main/tests/test_oa_hash_map.cpp:98:7: note: 'dummy' was declared here
   int dummy;
       ^

scene/resources/bit_mask.cpp:447:3: warning: 'next_i' may be used uninitialized in this function [-Wmaybe-uninitialized]
scene/resources/bit_mask.cpp:448:4: warning: 'next_j' may be used uninitialized in this function [-Wmaybe-uninitialized]
```

0 files changed, 0 insertions, 0 deletions