Fix uses of KeyedVector

Constructor for AudioFlinger::mAudioHwDevs was missing, and so
AudioFlinger::findSuitableHwDev_l() could return an undefined pointer
if a non-0 module wasn't found.

A KeyedVector of Plain Old Data (POD) element type must specify the
default value in the constructor, or else the default will be undefined.

Minor:
 - Parameter had wrong type in constructor for AudioSystem::gOutputs.
 - Remove obsolete AudioSystem::gStreamOutputMap.

Change-Id: I9841493e018440e559d8b8b0e4e748ba2b2d365b
diff --git a/media/libmedia/AudioSystem.cpp b/media/libmedia/AudioSystem.cpp
index 140fb66..193e488 100644
--- a/media/libmedia/AudioSystem.cpp
+++ b/media/libmedia/AudioSystem.cpp
@@ -37,7 +37,7 @@
 audio_error_callback AudioSystem::gAudioErrorCallback = NULL;
 // Cached values
 
-DefaultKeyedVector<audio_io_handle_t, AudioSystem::OutputDescriptor *> AudioSystem::gOutputs(0);
+DefaultKeyedVector<audio_io_handle_t, AudioSystem::OutputDescriptor *> AudioSystem::gOutputs(NULL);
 
 // Cached values for recording queries, all protected by gLock
 uint32_t AudioSystem::gPrevInSamplingRate;