[RFA/NEWS] Document the $_thread convenience variable

[Joel Brobecker <brobecker@adacore.com>]

Hello,

This document the new $_thread convenience variable (placed in the
`in GDB 7.2' section, since this was introduced after 7.1 and will
be part of 7.2).  If approved for HEAD, I will also port for the 7.2
branch.

Stan, you owe me one - fortunately for you, I'm cheap, because I cannot
drink alcohol ;-).

gdb/ChangeLog:

        * NEWS: Document $_thread.

OK to apply?

Thanks,
-- 
Joel

---
 gdb/NEWS |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index bf37ed8..59e8953 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -231,6 +231,10 @@ strace FN | FILE:LINE | *ADDR | -m MARKER_ID
 disassemble
   The disassemble command now supports "start,+length" form of two arguments.
 
+* New convenience variable: $_thread
+  This convenience variable contains the number of the current thread.
+  This may be useful inside breakpoint conditions, command scripts, etc.
+
 * Python scripting
 
 ** GDB now provides a new directory location, called the python directory,
-- 
1.7.1