Use SO_SNDBUFFORCE instead of SO_SNDBUF

When /proc/sys/net/core/wmem_max is smaller than kMaxMessageSize, we
need to override the limitation.

Bug: 37561460
Test: libappfuse_tests

Change-Id: Ibaac8db61290d661459fdc46f0ae8416f7db1d9e
diff --git a/libappfuse/FuseBuffer.cc b/libappfuse/FuseBuffer.cc
index b42a049..fd69849 100644
--- a/libappfuse/FuseBuffer.cc
+++ b/libappfuse/FuseBuffer.cc
@@ -141,8 +141,8 @@
     }
 
     constexpr int kMaxMessageSize = sizeof(FuseBuffer);
-    if (setsockopt(fds[0], SOL_SOCKET, SO_SNDBUF, &kMaxMessageSize, sizeof(int)) != 0 ||
-        setsockopt(fds[1], SOL_SOCKET, SO_SNDBUF, &kMaxMessageSize, sizeof(int)) != 0) {
+    if (setsockopt(fds[0], SOL_SOCKET, SO_SNDBUFFORCE, &kMaxMessageSize, sizeof(int)) != 0 ||
+        setsockopt(fds[1], SOL_SOCKET, SO_SNDBUFFORCE, &kMaxMessageSize, sizeof(int)) != 0) {
         PLOG(ERROR) << "Failed to update buffer size for socket";
         return false;
     }