improved CallStack a bit

- added a ctor that updates and dumps the stack immediately
- added a "logtag" parameter to dump()

Change-Id: Ie51c256071d282591752243bdb4f68cf9ff8829d
diff --git a/opengl/libs/EGL/egl_tls.cpp b/opengl/libs/EGL/egl_tls.cpp
index 41cfae1..52312a2 100644
--- a/opengl/libs/EGL/egl_tls.cpp
+++ b/opengl/libs/EGL/egl_tls.cpp
@@ -78,9 +78,7 @@
             char value[PROPERTY_VALUE_MAX];
             property_get("debug.egl.callstack", value, "0");
             if (atoi(value)) {
-                CallStack stack;
-                stack.update();
-                stack.dump();
+                CallStack stack(LOG_TAG);
             }
         }
         tls->error = error;