RFR: 6914: Fix windows check formatting script [v2]

[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:

  fail fast on calls

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

Changes:
  - all: https://git.openjdk.java.net/jmc/pull/114/files
  - new: https://git.openjdk.java.net/jmc/pull/114/files/2407fd76..f52e9342

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jmc&pr=114&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jmc&pr=114&range=00-01

  Stats: 4 lines in 1 file changed: 0 ins; 0 del; 4 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