RFA: Adapt linux-dp.exp to NPTL with debugging info

[Jim Blandy <jimb@redhat.com>]

I'm not sure this is the best approach to this.  If either Michael can
give me a push in the right direction, I'll do my best.

gdb/testsuite/ChangeLog:
2004-10-27  Jim Blandy  <jimb@redhat.com>

	* gdb.threads/linux-dp.exp: Fix output regexp to handle output
	under NPTL when there is debugging info available for libpthread.

Index: gdb/testsuite/gdb.threads/linux-dp.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.threads/linux-dp.exp,v
retrieving revision 1.9
diff -c -r1.9 linux-dp.exp
*** gdb/testsuite/gdb.threads/linux-dp.exp	14 May 2003 19:36:56 -0000	1.9
--- gdb/testsuite/gdb.threads/linux-dp.exp	27 Oct 2004 23:45:21 -0000
***************
*** 117,123 ****
  # Try setting a thread-specific breakpoint.
  gdb_breakpoint "print_philosopher thread 5"
  gdb_continue_to_breakpoint "thread 5's print"
! gdb_test "where" "print_philosopher.*philosopher.* from .*libpthread.*" \
  	"first thread-specific breakpoint hit"
  
  # Make sure it's catching the right thread.  Try hitting the
--- 117,129 ----
  # Try setting a thread-specific breakpoint.
  gdb_breakpoint "print_philosopher thread 5"
  gdb_continue_to_breakpoint "thread 5's print"
! # When there is no debugging info available for the thread library,
! # the backtrace entry for philosopher's caller looks like:
! #    #1  0x4001c548 in pthread_create () from /lib/libpthread.so.0
! # If you do have debug info, the output obviously depends more on the
! # exact library in use; under NPTL, you get:
! #    #2  0x0012b7fc in start_thread (arg=0x21) at pthread_create.c:264
! gdb_test "where" "print_philosopher.*philosopher.* \(from .*libpthread\|at pthread_create\).*" \
  	"first thread-specific breakpoint hit"
  
  # Make sure it's catching the right thread.  Try hitting the