add new errterm() function, to cleanup.

Reference: /n/patches.lsub.org/patch/errterm
Date: Tue May 15 18:08:30 CES 2012
Signed-off-by: nemo@lsub.org

--- /sys/man/2/error	Fri Apr 20 17:10:22 2012
+++ /sys/man/2/error	Fri May 11 18:51:34 2012
@@ -22,6 +22,10 @@
 .br
 .B
 int	errstacksize(void)
+.PP
+.B
+void	errterm(void)
+.br
 .SH DESCRIPTION
 These routiles are tools for error handling.
 .IR catcherror ,
@@ -39,7 +43,9 @@
 .I Errinit
 should be called before using any other. It should be called by each thread/process
 using the error handling mechanism. Its argument,
-indicaties the desired depth of the error stack for the calling process.
+indicaties the desired depth of the error stack for the calling process. Before exiting,
+.I errterm
+may be called to release the memory used for the error stack.
 .PP
 .I Catcherror
 install an exception handling point.
--- /sys/include/error.h	Fri Apr 20 17:10:22 2012
+++ /sys/include/error.h	Fri May 11 18:50:16 2012
@@ -12,6 +12,7 @@
 #pragma	varargck	argpos	error	1
 
 void	errinit(int stack);
+void	errterm(void);
 void	noerror(void);
 int	errstacksize(void);
 void	error(char* msg, ...);
--- /sys/src/liberror/error.c	Fri Apr 20 17:10:22 2012
+++ /sys/src/liberror/error.c	Fri May 11 18:54:01 2012
@@ -18,6 +18,12 @@
 	e->nlabel = stack;
 }
 
+void
+errterm(void)
+{
+	free(*__ep);
+}
+
 int
 errstacksize(void)
 {