RFR: 6914: Fix windows check formatting script [v3]

[Jean-Philippe Bempel]

> because mvn is itself a script we need to call with call command
> to get control back to the main script

Jean-Philippe Bempel has updated the pull request incrementally with one additional commit since the last revision:

  Add different exit code for each call

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Changes:
  - all: https://git.openjdk.java.net/jmc/pull/114/files
  - new: https://git.openjdk.java.net/jmc/pull/114/files/f52e9342..15c317ae

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmc&pr=114&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jmc&pr=114&range=01-02

  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jmc/pull/114.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/114/head:pull/114

PR: https://git.openjdk.java.net/jmc/pull/114