[apps][ion] Add <math.h> header to ensure building with all compilaters

[ion] In makefile, force the PATCH_LEVEL to be length 7

Change-Id: I67a7bd873a247dd42d0d1e845912cc8b71330d9e

apps/shared/interactive_curve_view_range_delegate.cpp

@@ -1,7 +1,8 @@
 #include "interactive_curve_view_range_delegate.h"
 #include "interactive_curve_view_range.h"
-#include <float.h>
 #include <cmath>
+#include <float.h>
+#include <math.h>
 
 namespace Shared {
 

apps/shared/memoized_curve_view_range.cpp

@@ -1,5 +1,6 @@
 #include "memoized_curve_view_range.h"
 #include <cmath>
+#include <math.h>
 #include <assert.h>
 #include <ion.h>
 

ion/Makefile

@@ -1,7 +1,7 @@
 GIT := $(shell command -v git 2> /dev/null)
 PATCH_LEVEL = NONE
 ifdef GIT
-  PATCH_LEVEL = `git rev-parse --short HEAD`
+  PATCH_LEVEL = `git rev-parse HEAD | head -c 7`
 endif
 
 SFLAGS += -Iion/include -DKD_CONFIG_H=1

poincare/src/complex.cpp

@@ -6,6 +6,7 @@ extern "C" {
 #include <float.h>
 }
 #include <cmath>
+#include <math.h>
 #include <poincare/complex_matrix.h>
 #include "layout/string_layout.h"
 #include "layout/baseline_relative_layout.h"

poincare/src/power.cpp

@@ -3,6 +3,7 @@ extern "C" {
 #include <stdlib.h>
 }
 #include <cmath>
+#include <math.h>
 #include <poincare/power.h>
 #include <poincare/multiplication.h>
 #include <poincare/opposite.h>