"warning gdb failed to set controlling terminal operation not permitted" when launching a GUI application.

Forked from #115

I am using:
•Ubuntu 16.04 (I know it is not supported officially)
•Latest VSCode version
•Latest "C/C++ for VSCode" version

My project structure looks like this:
•/home/lvier/mainProject/fooProject (source code)
•/home/lvier/mainProject/build/fooProject (binaries)

I am working in the sub-project "/home/lvier/mainProject/fooProject" and in "/home/lvier/mainProject/build/fooProject" there are many sub programs (lets say "foo", "foo_sub1", "foo_sub2" ...).

My goal:
I want to start the program "foo" (which starts all other foo_sub-programs) and then, I want to debug a certain sub program (let's say "foo_sub1") by attaching to it. I am also fine with starting and debugging in the same time as long as I can debug the sub-program "foo_sub1". The main project itself does not contain any executables.

2.Assume that "foo" is not running yet.
When using the "C++ Launch"-config, the program starts but no UI elements appear. Instead, it starts with a new terminal popping up which says "warning gdb failed to set controlling terminal operation not permitted" for a brief moment and in the internal console of VSCode, it states that it stops at a certain line of code (a breakpoint not defined by me) and prints
"Stopped due to shared library event (no libraries added or removed)
Loaded '/lib64/ld-linux-x86-64.so.2'. Symbols loaded.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1"."
From there I can't continue further and I have to manually terminate the program.

When I use GDB without VSCode, i.e. just by native terminal, my program is starting properly but with VSCode, there seem to be some issues currently.

This is my current, autogenerated config where I only edited the "cwd" and "program" paths (assume that the environment variable "${env.build_foo}" is set to "/home/lvier/mainProject/build/fooProject"):

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "C++ Launch",
            "type": "cppdbg",
            "request": "launch",
            "targetArchitecture": "x64",
            "program": "${env.build_foo}/foo",
            "args": [],
            "stopAtEntry": false,
            "cwd": "${workspaceRoot}",
            "environment": [],
            "externalConsole": true,
            "linux": {
                "MIMode": "gdb"
            },
            "osx": {
                "MIMode": "lldb"
            },
            "windows": {
                "MIMode": "gdb"
            }
        },
        {
            "name": "C++ Attach",
            "type": "cppdbg",
            "targetArchitecture": "x64",
            "request": "launch", // <-- "attach" is not allowed (anymore)! :(   
            "program": "${env.build_foo}/foo_sub1",
            "args": [],
            "stopAtEntry": false,
            "cwd": "${workspaceRoot}",
            "environment": [],
            "processId": "${command.pickProcess}",
            "externalConsole": false,
            "linux": {
                "MIMode": "gdb"
            },
            "osx": {
                "MIMode": "lldb"
            },
            "windows": {
                "MIMode": "gdb"
            }
        }
    ]
}

Start with the posted C++ Launch and C++ Attach configurations, especially externalConsole, cwd, program, and ${command.pickProcess}; compare their behavior with the same program under native GDB. Reproduce the controlling-terminal warning and the shared-library stop, then verify that the GUI launch continues and the foo_sub1 process can be attached without manual termination.