Propagate read-only scripts as SCRIPT LOAD.
Propagate read-only scripts as SCRIPT LOAD.

See issue #5250 and the new comments added to the code in this commit
for details.

charsyam/redis,ofirluzon/redis,ctripcorp/redis,neomantra/redis,oranagra/redis,spinlock/redis,neomantra/redis,soloestoy/redis,charsyam/redis,ctripcorp/redis,soloestoy/redis,pmem/redis,oranagra/redis,yossigo/redis,soveran/redis,soveran/redis,antirez/redis,spinlock/redis,oranagra/redis,antirez/redis,oranagra/redis,antirez/redis,yossigo/redis,PKRoma/redis,PKRoma/redis,nnog/redis,pmem/redis,neomantra/redis,pmem/redis,ofirluzon/redis,spinlock/redis,pmem/redis,yossigo/redis,spinlock/redis,soloestoy/redis,nnog/redis,soveran/redis,yossigo/redis,soloestoy/redis,charsyam/redis,charsyam/redis,soveran/redis,ofirluzon/redis,ctripcorp/redis,charsyam/redis,yossigo/redis,PKRoma/redis,antirez/redis,nnog/redis,PKRoma/redis,oranagra/redis,ofirluzon/redis,PKRoma/redis,nnog/redis,ctripcorp/redis,neomantra/redis,ofirluzon/redis,soloestoy/redis,neomantra/redis