RFR: 8356820: fixpath should allow + in paths on Windows

[Chihiro Ito]

When we run configure on Windows, fixpath is used, but this causes an error if the path contains +.

For example, when we unzip Temurin 24, the directory name created is jdk-24+36. When we specify this as the boot JDK, the following error is output and configure fails


configure: The path of BOOT_JDK_ARG, which is given as “/mnt/d/opt/jdks/temurin-24+36”, cannot be properly resolved.
configure: Please see the section “Special Considerations” in building.md.
configure: This is the error message given by fixpath:
fixpath: failure: Path '/mnt/d/opt/jdks/temurin-24+36' could not be converted to short path
configure: error: Cannot continue

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Commit messages:
 - 8356820: fixpath should allow + in paths on Windows

Changes: https://git.openjdk.org/jdk/pull/25197/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25197&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8356820
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/25197.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25197/head:pull/25197

PR: https://git.openjdk.org/jdk/pull/25197