Added safety checks to avoid running commands that will certainly fail
Generally, /p4/common/bin will be the same on all hosts in a Helix topolgy.
However, on any given machine, the /p4/<N>/bin/<EXE>_<N>_init scripts
should exist only for executables that run on that machine.
This change to upgrade.sh should work on machines even where only a
proxy or broker runs. Also, it will not generate errors in cases
where there is, say, a p4p_N_bin symlink in /p4/common/bin but no
/p4/N/bin/p4p_N_init script, which will a common situation since
/p4/common/bin will contain all executables used anywhere, while
/p4/N/bin is host-specific.
Also made cosmetic fixes and style convergence change.
In dump_edge.sh and recover_edge_dump.sh, just fixed cosmetic typos.