FIX: warning: implicit declaration of function ‘pipe2’

Author: Oldes

src/os/posix/host-lib.c

@@ -79,7 +79,9 @@ static void *Task_Ready;
 #define PATH_MAX 4096  // generally lacking in Posix
 #endif
 
-
+#ifndef USE_OLD_PIPE
+int pipe2(int pipefd[2], int flags); //to avoid "implicit-function-declaration" warning
+#endif
 
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