bug-14330: Initialize handle on Vulkan objects

https://cvs.khronos.org/bugzilla/show_bug.cgi?id=14330
Accepted in gl_common 7/27
diff --git a/include/vulkan.h b/include/vulkan.h
index a6a171f..0034d6f 100644
--- a/include/vulkan.h
+++ b/include/vulkan.h
@@ -61,8 +61,8 @@
     #endif
     #define VK_DEFINE_NONDISP_HANDLE(obj) \
         struct obj { \
-            obj() { } \
-            obj(uint64_t x) { handle = x; } \
+            obj() : handle(0) { } \
+            obj(uint64_t x) : handle(x) { } \
             obj& operator =(uint64_t x) { handle = x; return *this; } \
             bool operator==(const obj& other) const { return handle == other.handle; } \
             bool operator!=(const obj& other) const { return handle != other.handle; } \