Fixes for include path, jshell, and process issues.

• Put MD specific include files (e.g. jni_md.h) in a subdirectory named 'freebsd' rather than 'bsd'. [1]
• Remove the necessity to always have /usr/local/include in the header paths and linker paths. This allows jshell to use the system iconv.h rather than the third party one and link correctly. [2]
• Fix getting process commands and arguments on FreeBSD.
• Bump PORTREVISION.

All fixes need forward porting to openjdk12.

PR: 236754 [1], 236759 [2]
Submitted by: Kurt Miller [2]