Fix T64601 Error division by zero in GPUVertexFormat

The windows compiler use signed int by default for enums so that broke
the bit count I carefully did. Forcing uint fixes it.

source/blender/gpu/GPU_vertex_buffer.h

@@ -55,7 +55,7 @@ typedef struct GPUVertBuf {
   /** 0 indicates not yet allocated. */
   uint32_t vbo_id;
   /** Usage hint for GL optimisation. */
-  GPUUsageType usage : 2;
+  uint usage : 2;
   /** Data has been touched and need to be reuploaded to GPU. */
   uint dirty : 1;
   unsigned char *data; /* NULL indicates data in VRAM (unmapped) */

source/blender/gpu/GPU_vertex_format.h

@@ -56,8 +56,8 @@ typedef enum {
 } GPUVertFetchMode;
 
 typedef struct GPUVertAttr {
-  GPUVertFetchMode fetch_mode : 2;
-  GPUVertCompType comp_type : 3;
+  uint fetch_mode : 2;
+  uint comp_type : 3;
   /* 1 to 4 or 8 or 12 or 16 */
   uint comp_len : 5;
   /* size in bytes, 1 to 64 */