aaudio example: loop and add noise blip at start

Loop while starting and stopping or pausing/flushing.
Check framesWritten - framesRead.

Blip so we can tell if the beginning of the sound was cut off.
Add -t option for the high pitched prefix tone.

Test: this is a test
Change-Id: I2a642be67f4e80caad015254d006a0153b46e3f7
diff --git a/media/libaaudio/examples/utils/AAudioArgsParser.h b/media/libaaudio/examples/utils/AAudioArgsParser.h
index ada37e2..142b295 100644
--- a/media/libaaudio/examples/utils/AAudioArgsParser.h
+++ b/media/libaaudio/examples/utils/AAudioArgsParser.h
@@ -17,6 +17,8 @@
 #ifndef AAUDIO_EXAMPLE_ARGS_PARSER_H
 #define AAUDIO_EXAMPLE_ARGS_PARSER_H
 
+#define MAX_CHANNELS                     8
+
 #include <cctype>
 #include <unistd.h>
 #include <stdio.h>
@@ -39,6 +41,10 @@
     }
 
     void setChannelCount(int32_t channelCount) {
+        if (channelCount > MAX_CHANNELS) {
+            printf("Sorry, MAX of %d channels!\n", MAX_CHANNELS);
+            channelCount = MAX_CHANNELS;
+        }
         mChannelCount = channelCount;
     }