hal: Add new parameter in SA+ effects and resolve compilation issue

Add new parameter in SA+ effects to get latency introduced
by each effect. Use #ifdef instead of #if in environmentalreverb header
file since _cplusplus macro not being defined is raising errors.

Change-Id: I0d5e410414502ac2bef77f1cbd7b041e4f26844d
diff --git a/post_proc/equalizer.h b/post_proc/equalizer.h
index 7fec058..2cd06c2 100644
--- a/post_proc/equalizer.h
+++ b/post_proc/equalizer.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2014, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2013-2014, 2018, The Linux Foundation. All rights reserved.
  * Not a Contribution.
  *
  * Copyright (C) 2013 The Android Open Source Project
@@ -26,6 +26,8 @@
 #define INVALID_PRESET		 -2
 #define PRESET_CUSTOM		 -1
 
+#define EQ_PARAM_LATENCY 0x80000000
+
 extern const effect_descriptor_t equalizer_descriptor;
 
 typedef struct equalizer_context_s {