RFR: 8262828: Format of OS information is different on macOS

[Koichi Sakata]

This pull request derives from [JDK-8262507](https://github.com/openjdk/jdk/pull/2770). Unlike Windows and Linux, there isn't a newline after the OS label in os information of a hs_error log file and jcmd VM.info on macOS. So this adds the newline.

I checked output in a hs_err log and jcmd VM.info. 
OS:
uname: Darwin MacBook-Pro.local 19.6.0 Darwin Kernel Version 19.6.0: Tue Nov 10 00:10:30 PST 2020; root:xnu-6153.141.10~1/RELEASE_X86_64 x86_64
OS uptime: 2 days 5:13 hours
rlimit (soft/hard): STACK 8192k/65532k , CORE 0k/infinity , NPROC 5568/8352 , NOFILE 10240/65535 , AS infinity/infinity , CPU infinity/infinity , DATA infinity/infinity , FSIZE infinity/infinity , MEMLOCK infinity/infinity , RSS infinity/infinity
load average: 1.69 1.75 1.76

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Commit messages:
 - 8262828: Newline is needed after OS label on macOS for consistency

Changes: https://git.openjdk.java.net/jdk/pull/2824/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2824&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262828
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2824.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2824/head:pull/2824

PR: https://git.openjdk.java.net/jdk/pull/2824