Bug 1324606

+++ This bug was initially created as a clone of Bug #1321114 +++

Description of problem:
gdb>=7.10 (>=DTS-4.0) can no longer access shared libraries via sysroot "remote:" with gdbserver<=7.9.  RHEL-7 has gdbserver-7.6.1.
Installing DTS-4.0+ gdbserver workarounds that.

Version-Release number of selected component (if applicable):
devtoolset-4-gdb-7.11-57.el7

How reproducible:
Always.

Steps to Reproduce:
host1$ gdbserver-7.9 :1234 /root/inferior
                 ^^^
host2$ gdb-7.10 -ex 'set sysroot remote:' -ex 'file /root/inferior-copy-from-host1' -ex 'target remote host1:1234' 

Actual results:
warning: "remote:" is deprecated, use "target:" instead.
warning: sysroot set to "target:".
Reading symbols from /root/inferior-copy-from-host1...done.
Remote debugging using host1:1234
Reading /lib64/ld-linux-x86-64.so.2 from remote target...
warning: File transfers from remote targets can be slow. Use "set sysroot" to access files locally instead.
warning: Unable to find dynamic linker breakpoint function.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
GDB will be unable to debug shared library initializers
and track explicitly loaded dynamic code.
0x00007ffff7ddc430 in ?? ()
(gdb) b main
Breakpoint 1 at 0x40071a: file threadit.c, line 18.
(gdb) c
Continuing.
Reading /lib64/libpthread.so.0 from remote target...
Error while mapping shared library sections:
Could not open `target:/lib64/libpthread.so.0' as an executable file: Invalid argument
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Reading /lib64/libc.so.6 from remote target...
Error while mapping shared library sections:
Could not open `target:/lib64/libc.so.6' as an executable file: Invalid argument
Reading /lib64/ld-linux-x86-64.so.2 from remote target...
Error while mapping shared library sections:
Could not open `target:/lib64/ld-linux-x86-64.so.2' as an executable file: Invalid argument
Breakpoint 1, main () at threadit.c:18
18	  var++;
(gdb) info sharedlibrary 
From                To                  Syms Read   Shared Object Library
                                        No          /lib64/libpthread.so.0
                                        No          /lib64/libc.so.6
                                        No          /lib64/ld-linux-x86-64.so.2

Expected results:
host1$ gdbserver-7.9 :1234 /root/inferior
host2$ gdb-7.9 -ex 'set sysroot remote:' -ex 'file /root/inferior-copy-from-host1' -ex 'target remote host1:1234' 
Reading symbols from /root/inferior-copy-from-host1...done.
Remote debugging using host1:1234
Reading symbols from remote:/lib64/ld-linux-x86-64.so.2...(no debugging symbols found)...done.
0x00007ffff7ddc430 in _start () from remote:/lib64/ld-linux-x86-64.so.2
(gdb) b main
Breakpoint 1 at 0x40071a: file threadit.c, line 18.
(gdb) c
Continuing.
Breakpoint 1, main () at threadit.c:18
18	  var++;
(gdb) info sharedlibrary 
From                To                  Syms Read   Shared Object Library
0x00007ffff7ddbae0  0x00007ffff7df627a  Yes (*)     remote:/lib64/ld-linux-x86-64.so.2
0x00007ffff7bc48a0  0x00007ffff7bcf514  Yes (*)     remote:/lib64/libpthread.so.0
0x00007ffff781d3e0  0x00007ffff7960c10  Yes (*)     remote:/lib64/libc.so.6
(*): Shared library is missing debugging information.

Additional info:
Bug 1321114 did not really fix the compatibility.
It only added messages suggesting users to upgrade their gdbserver.