Make it clear to node-gyp which action arguments are paths

On Windows, node-gyp tries to be helpful by changing forward slashes
to backslashes and making paths relative to the source root rather
than the build directory, and indeed we rely on that. However, it has
to guess what's a path and what isn't. Previously, we worked around
that by manually stripping the prepended "..\", but the node-gyp
maintainers suggested a better workaround of using joined arguments
instead (`--foo=bar` instead of `--foo bar`).

binding.gyp

@@ -23,12 +23,13 @@
                     'action': [
                         'python3',
                         'node/build_node_bridge.py',
+                        # Use separated arguments for paths, joined arguments for non-paths.
                         '--out-dir', '<(PRODUCT_DIR)/',
-                        '--os-name', '<(NODE_OS_NAME)',
-                        '--configuration', '<(CONFIGURATION_NAME)',
+                        '--os-name=<(NODE_OS_NAME)',
+                        '--configuration=<(CONFIGURATION_NAME)',
                         '--cargo-build-dir', '<(INTERMEDIATE_DIR)/rust',
-                        '--cargo-target', '<(CARGO_ARCH)-<(CARGO_TARGET_SUFFIX)',
-                        '--node-arch', '<(target_arch)'
+                        '--cargo-target=<(CARGO_ARCH)-<(CARGO_TARGET_SUFFIX)',
+                        '--node-arch=<(target_arch)'
                         ],
                     'inputs': [],
                     'outputs': [

node/build_node_bridge.py

@@ -50,22 +50,16 @@ def main(args=None):
     if node_os_name is None:
         print('ERROR: --os-name is required')
         return 1
-    if node_os_name.startswith('..\\'):
-        node_os_name = node_os_name[3:]
 
     cargo_target = options.cargo_target
     if cargo_target is None:
         print('ERROR: --cargo-target is required')
         return 1
-    if cargo_target.startswith('..\\'):
-        cargo_target = cargo_target[3:]
 
     node_arch = options.node_arch
     if node_arch is None:
         print('ERROR: --node_arch is required')
         return 1
-    if node_arch.startswith('..\\'):
-        node_arch = node_arch[3:]
 
     out_dir = options.out_dir.strip('"') or os.path.join('build', configuration_name)