servo: Merge #9385 - Win32 support (from larsbergstrom:win32); r=frewsxcv,pcwalton,jdm,ecoal95

r? @frewsxcv for python stuff
r? @pcwalton for the "remove usage of Gaol" stuff for Win32
r? anybody else for misc cargo.lock updates, etc.

This replaces #7878.

This works best with https://github.com/servo/mozjs/pull/71, too, to enable static linking, but can be run without (via some PATH hackery).

The instructions are here, and will be added to a .md file in the repo once the mozjs changes also land:
https://hackpad.com/Servo-on-Windows-C1LPcI2bP25

I'd like to get these changes landed because I've been rebasing them for months, they're otherwise quite stable, and don't affect our other platforms and targets.

Source-Repo: https://github.com/servo/servo
Source-Revision: 525e77f64fc65ea2397b4ff3849f5b1f39386698

servo/python/mach_bootstrap.py

@@ -92,7 +92,9 @@ def _activate_virtualenv(topdir):
     if python is None:
         sys.exit("Python is not installed. Please install it prior to running mach.")
 
-    activate_path = os.path.join(virtualenv_path, "bin", "activate_this.py")
+    # Virtualenv calls its scripts folder "bin" on linux/OSX but "Scripts" on Windows, detect which one then use that
+    script_dir = "Scripts" if os.name == "nt" else "bin"
+    activate_path = os.path.join(virtualenv_path, script_dir, "activate_this.py")
     if not (os.path.exists(virtualenv_path) and os.path.exists(activate_path)):
         virtualenv = _get_exec(*VIRTUALENV_NAMES)
         if virtualenv is None: