llkd: add bit_wait_io to stack monitoring

This will discover if the I/O is starved.

Add the ability to search for " <symbol>.cfi+0x".

Cleaned up README.md to reflect current defaults.

Test: none
Bug: 113648929
Change-Id: I990a54f99de536406fd752a490e60f962380d71a
diff --git a/llkd/include/llkd.h b/llkd/include/llkd.h
index 2c62fca..cb56f34 100644
--- a/llkd/include/llkd.h
+++ b/llkd/include/llkd.h
@@ -48,7 +48,7 @@
 /* LLK_CHECK_MS_DEFAULT = actual timeout_ms / LLK_CHECKS_PER_TIMEOUT_DEFAULT */
 #define LLK_CHECKS_PER_TIMEOUT_DEFAULT 5
 #define LLK_CHECK_STACK_PROPERTY       "ro.llk.stack"
-#define LLK_CHECK_STACK_DEFAULT        "cma_alloc,__get_user_pages"
+#define LLK_CHECK_STACK_DEFAULT        "cma_alloc,__get_user_pages,bit_wait_io"
 #define LLK_BLACKLIST_PROCESS_PROPERTY "ro.llk.blacklist.process"
 #define LLK_BLACKLIST_PROCESS_DEFAULT  \
     "0,1,2,init,[kthreadd],[khungtaskd],lmkd,llkd,watchdogd,[watchdogd],[watchdogd/0]"