[Windows 10] Attach to process doesn't fetch source or any stats; fetching manually produces error

##### OS is Windows 10

When attaching to a process, the process is stopped as it should but the box where the code goes and all stats on the right hand side are left blank. So the behavior is different that in [this video](https://www.youtube.com/watch?v=aXHRJhsrIIs).
My code is a simple c++ programm that prints "Hello World!" every 3 seconds. I compiled with -g.
When I now try to point gdbgui to the source code by putting in the path to my helloworld.cpp on the left hand side, the command box prints out some odd error each time I 1)put in any letter 2)hit enter or 3)click "fetch source files"
Here's the error:

```
c/libgcc2.c",fullname="/home/keith/src/mingw/gcc-build/gcc-6.3.0-mingw32-cross-native/mingw32/libgcc/../../../src/gcc-6.3.0/libgcc/libgcc2.c"},{file="../../../src/gcc-6.3.0/libgcc/libgcc2.c",fullname="/home/keith/src/mingw/gcc-build/gcc-6.3.0-mingw32-cross-native/mingw32/libgcc/../../../src/gcc-6.3.0/libgcc/libgcc2.c"},{file="../../../src/gcc-6.3.0/libgcc/libgcc2.c",fullname="/home/keith/src/mingw/gcc-build/gcc-6.3.0-mingw32-cross-native/mingw32/libgcc/../../../src/gcc-6.3.0/libgcc/libgcc2.c"},{file="../../../src/gcc-6.3.0/libgcc/libgcc2.c",fullname="/home/keith/src/mingw/gcc-build/gcc-6.3.0-mingw32-cross-native/mingw32/libgcc/../../../src/gcc-6.3.0/libgcc/libgcc2.c"},{file="../../../src/gcc-6.3.0/libgcc/libgcc2.c",fullname="/home/keith/src/mingw/gcc-build/gcc-6.3.0-mingw32-cross-native/mingw32/libgcc/../../../src/gcc-6.3.0/libgcc/libgcc2.c"},{file="../../../src/gcc-6.3.0/libgcc/libgcc2.c",fullname="/home/keith/src/mingw/gcc-build/gcc-6.3.0-mingw32-cross-native/mingw32/libgcc/../../../src/gcc-6.3.0/libgcc/libgcc2.c"},{file="../../../src/gcc-6.3.0/libgcc/libgcc2.c",fullname="/home/keith/src/mingw/gcc-build/gcc-6.3.0-mingw32-cross-native/mingw32/libgcc/../../../src/gcc-6.3.0/libgcc/libgcc2.c"},{file="../../../src/gcc-6.3.0/libgcc/libgcc2.c",fullname="/home/keith/src/mingw/gcc-build/gcc-6.3.0-mingw32-cross-native/mingw32/libgcc/../../../src/gcc-6.3.0/libgcc/libgcc2.c"},{file="../../../src/gcc-6.3.0/libgcc/libgcc2.c",fullname="/home/keith/src/mingw/gcc-build/gcc-6.3.0-mingw32-cross-native/mingw32/libgcc/../../../src/gcc-6.3.0/libgcc/libgcc2.c"},{file="../../../src/gcc-6.3.0/libgcc/libgcc2.c",fullname="/home/keith/src/mingw/gcc-build/gcc-6.3.0-mingw32-cross-native/mingw32/libgcc/../../../src/gcc-6.3.0/libgcc/libgcc2.c"},{file="../../../src/gcc-6.3.0/libgcc/libgcc2.c",fullname="/home/keith/src/mingw/gcc-build/gcc-6.3.0-mingw32-cross-native/mingw32/libgcc/../../../src/gcc-6.3.0/libgcc/libgcc2.c"},{file="../../../src/gcc-6.3.0/libgcc/config/i386/cygwin.S",fullname="/home/keith/src/mingw/gcc-build/gcc-6.3.0-mingw32-cross-native/mingw32/libgcc/../../../src/gcc-6.3.0/libgcc/config/i386/cygwin.S"},{file="../../../src/gcc-6.3.0/libgcc/config/i386/cygwin.S",fullname="/home/keith/src/mingw/gcc-build/gcc-6.3.0-mingw32-cross-native/mingw32/libgcc/../../../src/gcc-6.3.0/libgcc/config/i386/cygwin.S"},{file="../../mingwrt/dllcrt1.c",fullname="/home/keith/src/mingw/mingw-wsl-outgoing/build/mingwrt/../../mingwrt/dllcrt1.c"}]

```

Also, the first time I git enter with the right path and file in the fetch source files textbox (`C:\Users\jcj-vb\C_helloworld\helloworld.cpp`) the command promt prints `File not found: C` in red letters. Although the path is definitely correct. Afterwards each enter produces that first error.

##### Describe your environment
* Operating system and version: Windows 10 Pro
* gdbgui version (`gdbgui -v`): 0.11.1.2
* gdb version (`gdb -v`): 7.6.1
* browser: Firefox
* I use normal MinGW
* python packages (`pip freeze`):
click==6.7
Flask==0.12.2
Flask-Compress==1.4.0
Flask-SocketIO==2.9.4
gdbgui==0.11.1.2
gevent==1.2.2
greenlet==0.4.13
itsdangerous==0.24
Jinja2==2.10
MarkupSafe==1.0
pygdbmi==0.8.2.0
Pygments==2.2.0
python-engineio==2.0.3
python-socketio==1.8.4
six==1.11.0
Werkzeug==0.14.1