display: Remove klockwork warnings and errors.

Remove all klockwork warnings and errors for libgralloc,
libhwcomposer, liboverlay, libqdutils, libqservice, libvirtual,
libexternal libraries to avoid buffer overflow and memory leaks.

Change-Id: I078143bcbcf5e4b342156bd8305a644566f7cc4b

libhwcomposer/hwc.cpp

@@ -764,6 +764,8 @@ static int hwc_device_open(const struct hw_module_t* module, const char* name,
     if (!strcmp(name, HWC_HARDWARE_COMPOSER)) {
         struct hwc_context_t *dev;
         dev = (hwc_context_t*)malloc(sizeof(*dev));
+        if(dev == NULL)
+            return status;
         memset(dev, 0, sizeof(*dev));
 
         //Initialize hwc context