test: ipc: unixsocket: Define local function in anonymous namespace

A local function in the unixsocket test is defined in the global
namespace without the static keyword. This compiles fine for now, but
will cause a missing declaration warning when we enable them. To prepare
for that, enclose the function declaration in an anonymous namespace.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

test/ipc/unixsocket.cpp

@@ -34,6 +34,8 @@ using namespace libcamera;
 using namespace std;
 using namespace std::chrono_literals;
 
+namespace {
+
 int calculateLength(int fd)
 {
 	lseek(fd, 0, 0);
@@ -43,6 +45,8 @@ int calculateLength(int fd)
 	return size;
 }
 
+} /* namespace */
+
 class UnixSocketTestSlave
 {
 public: