Unable to open source files on Windows due to forward slashes in File System browser

[svanimisetti]

When attaching to a process, the source files in the file system list and the file path bar/label are prepended with forward slash for windows paths (e.g., /c:\Users<userid>\Desktop\cpp_test\hello-world-1.cpp:1).

Steps to reproduce the behavior:

1. Create a executable using MinGW64 on Windows 10 with debug info (use -g -O0 flags)
2. Run executable and attach gdbgui to pid of executable
3. Click on "show filesystem" button and click on any files with windows path conventions (backward slash and drive-letter)
4. Observe the file path bar/label in gdbgui (forward slash in front of windows path prevents it from opening in file viewer)
5. Manually correct file path and enter it in the textbox/dropdown to open file in viewer
6. Cannot set breakpoint in the viewer (ERROR: No source file named c.)

OS: Windows 10 x86-64 gdbgui version (gdbgui -v): 0.13.2.2 gdb version (gdb -v): 7.11 browser [e.g. chrome, safari]: Chrome