Fix: match RenderPass::chan_id size with EXR_PASS_MAXCHAN

Missed in [0] which increased the size in openexr_multi.h but didn't
update RE_pipeline.h.

[0]: d5f1b9c2223333e03f2e4994171ad9df8c1c4f21⏎

source/blender/imbuf/IMB_openexr.hh

@@ -11,11 +11,11 @@
 /* API for reading and writing multi-layer EXR files. */
 
 /* XXX layer+pass name max 64? */
-/* This API also supports max 8 channels per pass now. easy to fix! */
 #define EXR_LAY_MAXNAME 64
 #define EXR_PASS_MAXNAME 64
 #define EXR_VIEW_MAXNAME 64
 #define EXR_TOT_MAXNAME 64
+/** Number of supported channels per pass (easy to change). */
 #define EXR_PASS_MAXCHAN 24
 
 struct StampData;

source/blender/render/RE_pipeline.h

@@ -52,7 +52,7 @@ struct RenderPass {
   struct RenderPass *next, *prev;
   int channels;
   char name[/*EXR_PASS_MAXNAME*/ 64];
-  char chan_id[8]; /* amount defined in IMB_openexr.hh */
+  char chan_id[/*EXR_PASS_MAXCHAN*/ 24];
 
   /**
    * Image buffer which contains data of this pass.