runtime, syscall: force EPOLLET to be positive

    
    The C definition is 1U << 31.  Reportedly on some systems GCC's
    -fgo-dump-spec can print this as -2147483648.
    
    Reviewed-on: https://go-review.googlesource.com/31448

From-SVN: r241347

gcc/go/gofrontend/MERGE

-68bb6a9875499037d3eccb79a1f92e1c7a476d58
+5346c7d15362a16efa0defaaeca63b1fce1c1523
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/go/runtime/netpoll_epoll.go

@@ -49,7 +49,7 @@ func netpollinit() {
 
 func netpollopen(fd uintptr, pd *pollDesc) int32 {
 	var ev epollevent
-	ev.events = _EPOLLIN | _EPOLLOUT | _EPOLLRDHUP | _EPOLLET
+	ev.events = _EPOLLIN | _EPOLLOUT | _EPOLLRDHUP | _EPOLLETpos
 	*(**pollDesc)(unsafe.Pointer(&ev.data)) = pd
 	if epollctl(epfd, _EPOLL_CTL_ADD, int32(fd), &ev) < 0 {
 		return int32(errno())

libgo/mkrsysinfo.sh

@@ -77,6 +77,12 @@ if grep '^const _epoll_data_offset ' ${OUT} >/dev/null 2>&1; then
       exit 1
   fi
 fi
+# Make sure EPOLLET is positive.
+if grep '^const _EPOLLET = [0-9]' gen-sysinfo.go; then
+  echo "const _EPOLLETpos = _EPOLLET" >> ${OUT}
+else
+  echo "const _EPOLLETpos = 0x80000000" >> ${OUT}
+fi
 # Make sure EPOLLRDHUP and EPOLL_CLOEXEC are defined.
 if ! grep '^const _EPOLLRDHUP' ${OUT} >/dev/null 2>&1; then
   echo "const _EPOLLRDHUP = 0x2000" >> ${OUT}

libgo/mksysinfo.sh

@@ -185,7 +185,15 @@ fi
 
 # epoll constants.
 grep '^const _EPOLL' gen-sysinfo.go |
+  grep -v EPOLLET |
   sed -e 's/^\(const \)_\(EPOLL[^= ]*\)\(.*\)$/\1\2 = _\2/' >> ${OUT}
+# Make sure EPOLLET is positive.
+if grep '^const _EPOLLET = [0-9]' gen-sysinfo.go; then
+  grep '^const _EPOLLET ' gen-sysinfo.go |
+    sed -e 's/^\(const \)_\(EPOLL[^= ]*\)\(.*\)$/\1\2 = _\2/' >> ${OUT}
+else
+  echo "const EPOLLET = 0x80000000" >> ${OUT}
+fi
 # Make sure EPOLLRDHUP and EPOLL_CLOEXEC are defined.
 if ! grep '^const EPOLLRDHUP' ${OUT} >/dev/null 2>&1; then
   echo "const EPOLLRDHUP = 0x2000" >> ${OUT}