Try escaped backslashes

Author: tannewt

ports/zephyr-cp/cptools/cpbuild.py

@@ -327,8 +327,11 @@ def __init__(self, srcdir: pathlib.Path, builddir: pathlib.Path, cmake_args):
 
         self._cflags_tempfile = tempfile.NamedTemporaryFile()
 
-        # Windows paths have \ as separator but gcc wants them escaped.
-        escaped_cflags = self.cflags.replace("\\", "\\\\")
+        # Windows paths have / as separator but gcc wants them as escaped backslashes.
+        if os.name == "nt":
+            escaped_cflags = self.cflags.replace("/", "\\\\")
+        else:
+            escaped_cflags = self.cflags
         print("writing:")
         print(escaped_cflags)
         self._cflags_tempfile.write(escaped_cflags.encode())