Removing bApproximate (part 1)

bApproximate is left over from long ago when the method to retrieve the system time might be 32-bit only or need correction. This is no longer needed, and already commented out of several sections of the sm5.1 base code. It can't be removed all at once just by deleting every instance of bApproximate, because it often refers to pointers that go elsewhere. so, this is the first part of a multi-stage removal process.

Other changes: remove samplerate() macro from RageSound, change some implicit casts to explicit.

src/RageSoundPosMap.cpp

@@ -110,13 +110,8 @@ void pos_map_impl::Cleanup()
 
 std::int64_t pos_map_queue::Search( std::int64_t iSourceFrame, bool *bApproximate ) const
 {
-	if( bApproximate )
-		*bApproximate = false;
-
 	if( IsEmpty() )
 	{
-		if( bApproximate )
-			*bApproximate = true;
 		return 0;
 	}
 
@@ -168,8 +163,6 @@ std::int64_t pos_map_queue::Search( std::int64_t iSourceFrame, bool *bApproximat
 		LOG->Trace("Audio frame was out of range of the data sent - possible buffer underflow? This is not always an error, however if you see it frequently there could be sound buffer problems.");
 	}
 
-	if( bApproximate )
-		*bApproximate = true;
 	return iClosestPosition;
 }