Haiku fixes (#3399)

* Allow running as root on Haiku.
* include unistd.h for ::read and ::write.
* Link libnetwork on Haiku.

src/CMakeLists.txt

@@ -121,6 +121,10 @@ if(LMMS_HAVE_OSS AND LMMS_BUILD_OPENBSD)
     SET(EXTRA_LIBRARIES "-lossaudio")
 endif()
 
+IF(LMMS_BUILD_HAIKU)
+	SET(EXTRA_LIBRARIES "-lnetwork")
+ENDIF()
+
 SET(LMMS_REQUIRED_LIBS
 	${CMAKE_THREAD_LIBS_INIT}
 	${QT_LIBRARIES}

src/core/main.cpp

@@ -251,7 +251,7 @@ int main( int argc, char * * argv )
 		}
 	}
 
-#ifndef LMMS_BUILD_WIN32
+#if !defined(LMMS_BUILD_WIN32) && !defined(LMMS_BUILD_HAIKU)
 	if ( ( getuid() == 0 || geteuid() == 0 ) && !allowRoot )
 	{
 		printf( "LMMS cannot be run as root.\nUse \"--allowroot\" to override.\n\n" );