able to find libjli.so from RPATH because argv[0] points to the symlink.
Note it seems Linux does not have the problem when /proc/self/exe exists.
If it does not exist, it also fails to find libjli.so. Clean up patches
while I am here.
- Move jspawnhelper to jre/lib/<arch> directory as Solaris does. [1]
- Add sigset(2) wrapper for libsig.so.
- Disable UseMembar by default.
Inspired by: Kurt Miller (kurt at intricatesoftware dot com) [1]
