Support Valgrind attachments broken by the PIE support.
* auxv.c: Include gdbcore.h.
(procfs_xfer_auxv): Make static. Reduce its comment. Drop its
parameters ops, object and annex. Remove their assertions.
(ld_so_xfer_auxv, memory_xfer_auxv): New function.
* auxv.h (procfs_xfer_auxv): Remove comment. Rename to ...
(memory_xfer_auxv): ... here.
* linux-nat.c (linux_xfer_partial): Rename procfs_xfer_auxv to
memory_xfer_auxv.
* procfs.c (procfs_xfer_partial): Likewise.
* solib-svr4.c (svr4_relocate_main_executable): New prototype.
(svr4_special_symbol_handling): Call svr4_relocate_main_executable.
(svr4_solib_create_inferior_hook): Conditionalize the
svr4_relocate_main_executable call.
gdb/testsuite/
* gdb.base/valgrind-db-attach.exp, gdb.base/valgrind-db-attach.c: New.
