PATCH (doc): update THREADS file in libobjc

[Nicola Pero <nicola at brainstorm dot co dot uk>]

Looks like it would be appropriate to update the doc before 3.0.

Index: ChangeLog
===================================================================
RCS file: /cvs/gcc/gcc/libobjc/ChangeLog,v
retrieving revision 1.51.2.7
diff -u -r1.51.2.7 ChangeLog
--- ChangeLog   2001/05/25 07:15:55     1.51.2.7
+++ ChangeLog   2001/06/05 14:37:23
@@ -1,3 +1,9 @@
+Tue Jun  5 18:41:42 2001  Nicola Pero  <n.pero@mi.flashnet.it>
+
+       * THREADS: Updated: explain that when we compile libobjc inside
+       GCC, we always use thr-objc.c as a backend, which uses GCC's
+       thread code.
+
 2001-05-25  Ovidiu Predescu  <ovidiu@cup.hp.com>
 
        * init.c (__objc_send_message_in_list): When setting a new entry


Index: THREADS
===================================================================
RCS file: /cvs/gcc/gcc/libobjc/THREADS,v
retrieving revision 1.2
diff -u -r1.2 THREADS
--- THREADS     1999/09/04 15:09:19     1.2
+++ THREADS     2001/06/05 14:03:01
@@ -102,22 +102,25 @@
 
 The backend is composed of a file with the necessary code to map the ObjC
 thread and mutex to a platform specific implementation.  For example, the
-file thr-solaris.c contains the implementation for Solaris.  When you 
-configure GCC, it attempts to pick an appropriate backend file for the
-target platform; however, you can override this choice by assign the
-OBJC_THREAD_FILE make variable to the basename of the backend file.  This
-is especially useful on platforms which have multiple thread libraries.
-For example:
+file thr-solaris.c contains the implementation for Solaris.  
 
-       make OBJC_THREAD_FILE=thr-posix
+If you are compiling libobjc as part of GCC, the thr-objc.c backend is
+always used; this backend uses GCC's gthread code.  The thread system is
+automatically configured when GCC is configured.  Important: make sure you
+configure GCC using `--enable-threads' if you want threads !
 
-would indicate that the generic posix backend file, thr-posix.c, should be
-compiled with the ObjC runtime library.  If your platform does not support
-threads then you should specify the OBJC_THREAD_FILE=thr-single backend file
-to compile the ObjC runtime library without thread or mutex support; note
-that programs which rely upon the ObjC thread and mutex functions will
-compile and link correctly but attempting to create a thread or mutex will
-result in an error.
+If you want to compile libobjc standalone, then you would need to
+modify the configure.in and makefiles for it; and you need to pick an
+appropriate backend file for the target platform; you make this choice
+by assigning the OBJC_THREAD_FILE make variable to the basename of the
+backend file.  For example, OBJC_THREAD_FILE=thr-posix would indicate
+that the generic posix backend file, thr-posix.c, should be compiled
+with the ObjC runtime library.  If your platform does not support
+threads then you should specify the OBJC_THREAD_FILE=thr-single
+backend file to compile the ObjC runtime library without thread or
+mutex support; note that programs which rely upon the ObjC thread and
+mutex functions will compile and link correctly but attempting to
+create a thread or mutex will result in an error.
 
 It is questionable whether it is really necessary to have both a
 frontend and backend function for all available functionality.  On the