libc: Stub out scanf()

libs/libc/include/stdio.h

@@ -143,6 +143,7 @@ extern "C"
 
     int sscanf(const char*, const char*, ...); // Not implemented.
     int fscanf(FILE*, const char*, ...);       // Not implemented.
+    int scanf(const char*, ...);               // Not implemented.
 
     /* Writes the string str followed by a trailing newline to stdout. */
     int puts(const char* str);

libs/libc/src/stdio.cpp

@@ -64,6 +64,11 @@ extern "C"
         NOT_IMPLEMENTED("fscanf");
     }
 
+    int scanf(const char*, ...)
+    {
+        NOT_IMPLEMENTED("scanf");
+    }
+
     int rename(const char*, const char*)
     {
         NOT_IMPLEMENTED("rename");