Revert "LibM: Always include <math.h> instead of <LibM/math.h>"

This reverts commit dc12cbca41.

Sadly this broke the build due to some confusion about <new>.
Reverting until this can be solved fully.

Applications/SoundPlayer/SampleWidget.cpp

@@ -27,7 +27,7 @@
 #include "SampleWidget.h"
 #include <LibAudio/Buffer.h>
 #include <LibGUI/Painter.h>
-#include <math.h>
+#include <LibM/math.h>
 
 SampleWidget::SampleWidget()
 {