Remove all \bcode / \ecode cruft; this is no longer needed.  See previous
checkin of myformat.sty.

Change "\renewcommand{\indexsubitem}{(...)}" to "\setindexsubitem{(...)}"
everywhere.

Some other minor nits that I happened to come across.
diff --git a/Doc/libthread.tex b/Doc/libthread.tex
index ae11823..24ebac5 100644
--- a/Doc/libthread.tex
+++ b/Doc/libthread.tex
@@ -20,7 +20,7 @@
 
 It defines the following constant and functions:
 
-\renewcommand{\indexsubitem}{(in module thread)}
+\setindexsubitem{(in module thread)}
 \begin{excdesc}{error}
 Raised on thread-specific errors.
 \end{excdesc}
@@ -64,7 +64,7 @@
 
 Lock objects have the following methods:
 
-\renewcommand{\indexsubitem}{(lock method)}
+\setindexsubitem{(lock method)}
 \begin{funcdesc}{acquire}{\optional{waitflag}}
 Without the optional argument, this method acquires the lock
 unconditionally, if necessary waiting until it is released by another