sdm: add check for disabling external animation

In current design the flag passed from clients is used to
disable external animation. Refine this flag to two parts,
one is to indicate whether animation is present, another
is to check the system property and disable external
animation. So other functions can know the presence of
animation layers if necessary.

CRs-fixed: 1019601

Change-Id: Ib6ffb7a28d6935b86bc93abc82049b77b3ddcd08

sdm/include/utils/debug.h

@@ -76,6 +76,7 @@ class Debug {
   static bool IsScalarDisabled();
   static bool IsUbwcTiledFrameBuffer();
   static bool IsAVRDisabled();
+  static bool IsExtAnimDisabled();
   static bool GetProperty(const char *property_name, char *value);
   static bool SetProperty(const char *property_name, const char *value);