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
diff --git a/libhwcomposer/hwc.cpp b/libhwcomposer/hwc.cpp
index f157f6b..e27368d 100644
--- a/libhwcomposer/hwc.cpp
+++ b/libhwcomposer/hwc.cpp
@@ -764,6 +764,8 @@
     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