fix(msvs): avoid fixing path for arguments with "=" (#143)

They are probably not paths, and V8 uses an argument like that, so the
fix is needed in Node.js

Refs: nodejs/node#42115

pylib/gyp/generator/msvs.py

@@ -423,12 +423,15 @@ def _BuildCommandLineForRuleRaw(
         command.insert(0, "call")
         # Fix the paths
         # TODO(quote): This is a really ugly heuristic, and will miss path fixing
-        #              for arguments like "--arg=path" or "/opt:path".
-        # If the argument starts with a slash or dash, it's probably a command line
-        # switch
+        #              for arguments like "--arg=path", arg=path, or "/opt:path".
+        # If the argument starts with a slash or dash, or contains an equal sign,
+        # it's probably a command line switch.
         # Return the path with forward slashes because the command using it might
         # not support backslashes.
-        arguments = [i if (i[:1] in "/-") else _FixPath(i, "/") for i in cmd[1:]]
+        arguments = [
+            i if (i[:1] in "/-" or "=" in i) else _FixPath(i, "/")
+            for i in cmd[1:]
+        ]
         arguments = [i.replace("$(InputDir)", "%INPUTDIR%") for i in arguments]
         arguments = [MSVSSettings.FixVCMacroSlashes(i) for i in arguments]
         if quote_cmd: