The Library LIBRSX.A contains signal,spawnve and ptrace stuff for DJGPP.

Copy the files
LIBRSX.A    -> \djgpp\lib

_PROCESS.H  -> \djgpp\include\sys
_USER.H     -> \djgpp\include\sys
_PTRACE.H   -> \djgpp\include\sys
_REG.H	    -> \djgpp\include\sys
_SIGNAL.H   -> \djgpp\include\sys