llkd: default enabled for userdebug

If LLK_ENABLE_DEFAULT is false, then check "ro.llk.enable" for "eng",
also the default value if not set, and then check if userdebug build
to establish a default of true for enable.  Same for
ro.khungtask.enable.

Test: llkd_unit_test report eng status on "userdebug" or "user" builds
Bug: 33808187
Bug: 72838192
Change-Id: I2adb23c7629dccaa2856c50bccbf4e363703c82c
diff --git a/llkd/include/llkd.h b/llkd/include/llkd.h
index 2ae28ed..bd0739b 100644
--- a/llkd/include/llkd.h
+++ b/llkd/include/llkd.h
@@ -30,9 +30,11 @@
 unsigned llkCheckMilliseconds(void);
 
 /* clang-format off */
-#define LLK_ENABLE_PROPERTY            "ro.llk.enable"
-#define LLK_ENABLE_DEFAULT             false
-#define KHT_ENABLE_PROPERTY            "ro.khungtask.enable"
+#define LLK_ENABLE_WRITEABLE_PROPERTY  "llk.enable"
+#define LLK_ENABLE_PROPERTY            "ro." LLK_ENABLE_WRITEABLE_PROPERTY
+#define LLK_ENABLE_DEFAULT             false /* "eng" and userdebug true */
+#define KHT_ENABLE_WRITEABLE_PROPERTY  "khungtask.enable"
+#define KHT_ENABLE_PROPERTY            "ro." KHT_ENABLE_WRITEABLE_PROPERTY
 #define LLK_MLOCKALL_PROPERTY          "ro.llk.mlockall"
 #define LLK_MLOCKALL_DEFAULT           true
 #define LLK_TIMEOUT_MS_PROPERTY        "ro.llk.timeout_ms"