Fix doSysreqC/D's return address getting overwritten on nested native calls
Fix doSysreqC/D's return address getting overwritten on nested native calls

This also fixes issue #24 "SIGSEGV in filterscript with streamer plugin"

Zeex/samp-plugin-jit,Zeex/samp-plugin-jit,oscar-broman/samp-plugin-jit,oscar-broman/samp-plugin-jit