Don't depend on the PLATFORM variable being defined

Change-Id: Ia1d0e5f320dfc0c6ab1cf8a588c297cbbc3c0df3

poincare/src/power.cpp

@@ -1,8 +1,5 @@
-#if PLATFORM==simulator
-#include <cmath>
-#endif
-
 #include <poincare/power.h>
+#include <math.h>
 #include "layout/exponent_layout.h"
 
 Power::Power(Expression * base, Expression * exponent) :
@@ -16,12 +13,7 @@ Power::~Power() {
 }
 
 float Power::approximate(Context& context) {
-#if PLATFORM==simulator
   return powf(m_base->approximate(context), m_exponent->approximate(context));
-#else
-  // TODO(fraimundo): do this for real
-  return 1f;
-#endif
 }
 
 ExpressionLayout * Power::createLayout(ExpressionLayout * parent) {