RFR: 8258925: configure script failed on WSL [v4]

[Yasumasa Suenaga]

> I ran configure script on WSL 1, but it failed as below:
> 
> $ bash configure --enable-debug --with-boot-jdk=/mnt/d/Java/jdk-15.0.1
> 
>     :
> 
> configure: Found potential Boot JDK using configure arguments
> configure: The command for java_to_test, which resolves as "/mnt/d/Java/jdk-15.0.1/bin/java", can not be found.
> configure: error: Cannot locate /mnt/d/Java/jdk-15.0.1/bin/java
> configure exiting with result code 1
> 
> `fixpath.sh` attempts to run `$PATHTOOL` with `.exe` if it fails with original path, but `.exe` would not be added even if `$path.exe` exists.

Yasumasa Suenaga has updated the pull request incrementally with one additional commit since the last revision:

  Refactoring

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1889/files
  - new: https://git.openjdk.java.net/jdk/pull/1889/files/37498adf..1294adde

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1889&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1889&range=02-03

  Stats: 8 lines in 1 file changed: 4 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1889.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1889/head:pull/1889

PR: https://git.openjdk.java.net/jdk/pull/1889