RFR: 8280531: Remove unused DeferredCloseInputStream

[Andrey Turbanov]

Class DeferredCloseInputStream is unused since removing of Solaris support
https://github.com/openjdk/jdk/blob/9fe4b69c1a1120e1d761730495c3cfac8f179d13/src/java.base/unix/classes/java/lang/ProcessImpl.java#L80-L81

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Commit messages:
 - [PATCH] Remove unused DeferredCloseInputStream

Changes: https://git.openjdk.java.net/jdk/pull/7135/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7135&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280531
  Stats: 106 lines in 1 file changed: 0 ins; 104 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7135.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7135/head:pull/7135

PR: https://git.openjdk.java.net/jdk/pull/7135