Back quotes and double quotes must not be escaped in: Cannot convert \"$unix_path\" to Windows path

# Symptom

```
Runnable configure script is not present
Generating runnable configure script at /jdk/build/.configure-support/generated-configure.sh
Using autoconf at /usr/local/bin/autoconf [autoconf (GNU Autoconf) 2.69]
stdin:88: warning: back quotes and double quotes must not be escaped in: Cannot convert \"$unix_path\" to Windows path
/jdk/make/autoconf/util_windows.m4:66: UTIL_REWRITE_AS_WINDOWS_MIXED_PATH is expanded from...
/jdk/make/autoconf/util_windows.m4:149: UTIL_MAKE_WINDOWS_SPACE_SAFE_WSL is expanded from...
/jdk/make/autoconf/util_windows.m4:229: UTIL_FIXUP_PATH_WSL is expanded from...
/jdk/make/autoconf/util_paths.m4:110: UTIL_FIXUP_PATH is expanded from...
/jdk/make/autoconf/basic.m4:107: BASIC_SETUP_PATHS is expanded from...
stdin:88: the top level
stdin:104: warning: back quotes and double quotes must not be escaped in: Cannot convert \"$unix_path\" to Windows path
```

# Reproduce

On Linux
```
rm build -rf
bash configure ...
```