genesys: Add missing <cmath> includes

backend/genesys/genesys.cpp

@@ -68,6 +68,7 @@
 #include "../include/sane/sanei_magic.h"
 
 #include <array>
+#include <cmath>
 #include <cstring>
 #include <fstream>
 #include <iterator>

backend/genesys/image_pipeline.cpp

@@ -46,6 +46,7 @@
 #include "image_pipeline.h"
 #include "image.h"
 #include "low.h"
+#include <cmath>
 #include <numeric>
 
 namespace genesys {

backend/genesys/low.cpp

@@ -48,6 +48,7 @@
 #include "assert.h"
 
 #include <cstdio>
+#include <cmath>
 #include <vector>
 
 /* ------------------------------------------------------------------------ */