Implement a "generate-core-file" command in gdb, save target state.
* gcore.c: New file. Implement new command 'generate-core-file'.
Save a corefile image of the current state of the inferior.
* linux-proc.c: Add linux-specific code for saving corefiles.
* target.h (struct target_ops): Add new target vectors for saving
corefiles; to_find_memory_regions and to_make_corefile_notes.
(target_find_memory_regions): New macro.
(target_make_corefile_notes): New macro.
* target.c (update_current_target): Inherit new target methods.
(dummy_find_memory_regions): New place-holder method.
(dummy_make_corefile_notes): New place-holder method.
(init_dummy_target): Initialize new dummy target vectors.
* exec.c (exec_set_find_memory_regions): New function.
Allow the exec_ops vector for memory regions to be taken over.
(exec_make_note_section): New function, target vector method.
* defs.h (exec_set_find_memory_regions): Export prototype.
* procfs.c (proc_find_memory_regions): New function, corefile method.
(procfs_make_note_section): New function, corefile method.
(init_procfs_ops): Set new target vector pointers.
(find_memory_regions_callback): New function.
(procfs_do_thread_registers): New function.
(procfs_corefile_thread_callback): New function.
* sol-thread.c (sol_find_memory_regions): New function.
(sol_make_note_section): New function.
(init_sol_thread_ops): Initialize new target vectors.
* inftarg.c (inftarg_set_find_memory_regions): New function.
Allow to_find_memory_regions vector to be taken over.
(inftarg_set_make_corefile_notes): New function.
Allow to_make_corefile_notes vector to be taken over.
* thread-db.c (thread_db_new_objfile): Don't activate thread-db
interface layer if not target_has_execution (may be a corefile).
* config/i386/linux.mh: Add gcore.o to NATDEPFILES.
* config/sparc/sun4sol2.mh: Ditto.
* config/alpha/alpha-linux.mh: Ditto.
* config/arm/linux.mh: Ditto.
* config/i386/x86-64linux.mh: Ditto.
* config/ia64/linux.mh: Ditto.
* config/m68k/linux.mh: Ditto.
* config/mips/linux.mh: Ditto.
* config/powerpc/linux.mh: Ditto.
* config/sparc/linux.mh: Ditto.
