mksysinfo: Define MADV_ constants for madvise.

From-SVN: r184752

libgo/mksysinfo.sh

@@ -191,6 +191,8 @@ grep '^const _PROT_' gen-sysinfo.go | \
   sed -e 's/^\(const \)_\(PROT_[^= ]*\)\(.*\)$/\1\2 = _\2/' >> ${OUT}
 grep '^const _MAP_' gen-sysinfo.go | \
   sed -e 's/^\(const \)_\(MAP_[^= ]*\)\(.*\)$/\1\2 = _\2/' >> ${OUT}
+grep '^const _MADV_' gen-sysinfo.go | \
+  sed -e 's/^\(const \)_\(MADV_[^= ]*\)\(.*\)$/\1\2 = _\2/' >> ${OUT}
 
 # Process status constants.
 grep '^const _W' gen-sysinfo.go |