Cycles: Move system headers include to the top of the files

This is a good practice to do anyway, plus it'll help with the upcoming change.

intern/cycles/kernel/osl/osl_globals.h

@@ -20,7 +20,6 @@
 #ifdef WITH_OSL
 
 #include <OSL/oslexec.h>
-#include <cmath>
 
 #include "util_map.h"
 #include "util_param.h"

intern/cycles/kernel/osl/osl_shader.cpp

@@ -14,6 +14,8 @@
  * limitations under the License
  */
 
+#include <OSL/oslexec.h>
+
 #include "kernel_compat_cpu.h"
 #include "kernel_montecarlo.h"
 #include "kernel_types.h"
@@ -34,7 +36,6 @@
 
 #include "attribute.h"
 
-#include <OSL/oslexec.h>
 
 CCL_NAMESPACE_BEGIN
 

intern/cycles/render/shader.h

@@ -17,6 +17,10 @@
 #ifndef __SHADER_H__
 #define __SHADER_H__
 
+#ifdef WITH_OSL
+#  include <OSL/oslexec.h>
+#endif
+
 #include "attribute.h"
 #include "kernel_types.h"
 
@@ -25,10 +29,6 @@
 #include "util_string.h"
 #include "util_types.h"
 
-#ifdef WITH_OSL
-#include <OSL/oslexec.h>
-#endif
-
 CCL_NAMESPACE_BEGIN
 
 class Device;