examples/decoding_encoding: store temporary files in current dir

Do not clutter the temporary directory with files, also "/tmp" is not
always available, e.g. in Windows.

Also add the clean-test Makefile rule, which will clean the generated
files.

doc/examples/Makefile

@@ -23,9 +23,12 @@ OBJS=$(addsuffix .o,$(EXAMPLES))
 decoding_encoding: LDLIBS += -lm
 muxing:            LDLIBS += -lm
 
-.phony: all clean
+.phony: all clean-test clean
 
 all: $(OBJS) $(EXAMPLES)
 
-clean:
+clean-test:
+	rm -rf test*.pgm test.h264 test.mp2 test.sw test.mpg
+
+clean: clean-test
 	rm -rf $(EXAMPLES) $(OBJS)

doc/examples/decoding_encoding.c

@@ -606,18 +606,18 @@ int main(int argc, char **argv)
     avcodec_register_all();
 
     if (argc <= 1) {
-        audio_encode_example("/tmp/test.mp2");
-        audio_decode_example("/tmp/test.sw", "/tmp/test.mp2");
+        audio_encode_example("test.mp2");
+        audio_decode_example("test.sw", "test.mp2");
 
-        video_encode_example("/tmp/test.h264", AV_CODEC_ID_H264);
-        video_encode_example("/tmp/test.mpg", AV_CODEC_ID_MPEG1VIDEO);
-        filename = "/tmp/test.mpg";
+        video_encode_example("test.h264", AV_CODEC_ID_H264);
+        video_encode_example("test.mpg", AV_CODEC_ID_MPEG1VIDEO);
+        filename = "test.mpg";
     } else {
         filename = argv[1];
     }
 
-    //    audio_decode_example("/tmp/test.sw", filename);
-    video_decode_example("/tmp/test%d.pgm", filename);
+    //    audio_decode_example("test.sw", filename);
+    video_decode_example("test%02d.pgm", filename);
 
     return 0;
 }