[SPARK-9607] [SPARK-9608] fix zinc-port handling in build/mvn
[SPARK-9607] [SPARK-9608] fix zinc-port handling in build/mvn

- pass `$ZINC_PORT` to zinc status/shutdown commands
- fix path check that sets `$ZINC_INSTALL_FLAG`, which was incorrectly
  causing zinc to be shutdown and restarted every time (with mismatched
  ports on those commands to boot)
- pass `-DzincPort=${ZINC_PORT}` to maven, to use the correct zinc port
  when building

Author: Ryan Williams <ryan.blake.williams@gmail.com>

Closes #7944 from ryan-williams/zinc-status and squashes the following commits:

619c520 [Ryan Williams] fix zinc status/shutdown commands

(cherry picked from commit e27a8c4cb3564f1b2d1ee5445dff341c8e0087b0)
Signed-off-by: Sean Owen <291c18f3fb7528c712d9098b0e50a515ea0b91d5@cloudera.com>

andrewor14/iolap,andrewor14/iolap,andrewor14/iolap,andrewor14/iolap,andrewor14/iolap,andrewor14/iolap,andrewor14/iolap