gspawn: safe_fdwalk/safe_closefrom for Solaris 11.3/11.4
When F_CLOSEFROM is defined, we know that closefrom() is signal safe. And use F_NEXTFD/F_PREVFD for fdwalk when they are available.
Closes #2429 (closed)
When F_CLOSEFROM is defined, we know that closefrom() is signal safe. And use F_NEXTFD/F_PREVFD for fdwalk when they are available.
Closes #2429 (closed)