When creating a thread specific breakpoint GDB will warn about other 
breakpoints set on the same address even when they are specific to 
another thread.

The attached patch prevents it warning about breakpoints from other 
threads. When a non-thread specific breakpoint is created, or already 
exists, the warning is still given, but is annotated with the thread 
information. When not using thread specific breakpoints the behaviour 
should remain unaltered.

:ADDPATCH breakpoint.c:

Andrew Stubbs