File bindings/s2/config.h artifact bea197f7dc part of check-in 1c6aeaf5ce

#define S2_OS_UNIX 1
#define S2_HAVE_REALPATH 1
#define S2_HAVE_STAT 1
#define S2_HAVE_CHDIR 1
#define CWAL_OBASE_ISA_HASH 1