init: Enable ANDROID_BASE_UNIQUE_FD_DISABLE_IMPLICIT_CONVERSION

From the unique_fd.h header file: "unique_fd's operator int is
dangerous, but we have way too much code that depends on it, so make
this opt-in at first."

From the Google C++ style guide: "Do not define implicit conversions."
See also go/cstyle#Implicit_Conversions.

Hence this CL that disables unique_fd::operator int().

Change-Id: I28d94755d5408f63e5819da8d1cbc285057f867f
Signed-off-by: Bart Van Assche <bvanassche@google.com>
diff --git a/init/epoll.cpp b/init/epoll.cpp
index fd1af4f..cd73a0c 100644
--- a/init/epoll.cpp
+++ b/init/epoll.cpp
@@ -57,7 +57,7 @@
             .events = events,
             .data.fd = fd,
     };
-    if (epoll_ctl(epoll_fd_, EPOLL_CTL_ADD, fd, &ev) == -1) {
+    if (epoll_ctl(epoll_fd_.get(), EPOLL_CTL_ADD, fd, &ev) == -1) {
         Result<void> result = ErrnoError() << "epoll_ctl failed to add fd";
         epoll_handlers_.erase(fd);
         return result;
@@ -66,7 +66,7 @@
 }
 
 Result<void> Epoll::UnregisterHandler(int fd) {
-    if (epoll_ctl(epoll_fd_, EPOLL_CTL_DEL, fd, nullptr) == -1) {
+    if (epoll_ctl(epoll_fd_.get(), EPOLL_CTL_DEL, fd, nullptr) == -1) {
         return ErrnoError() << "epoll_ctl failed to remove fd";
     }
     auto it = epoll_handlers_.find(fd);
@@ -88,7 +88,7 @@
     }
     const auto max_events = epoll_handlers_.size();
     epoll_event ev[max_events];
-    auto num_events = TEMP_FAILURE_RETRY(epoll_wait(epoll_fd_, ev, max_events, timeout_ms));
+    auto num_events = TEMP_FAILURE_RETRY(epoll_wait(epoll_fd_.get(), ev, max_events, timeout_ms));
     if (num_events == -1) {
         return ErrnoError() << "epoll_wait failed";
     }