Remove BlockChange from packed structs

pragma pack (push, 1) forces alignment to 1-byte.
While reordering the fields does help with memory accesses, it only
works if the compiler can ensure 2-byte alignments for this struct.

include/globals.h

@@ -172,8 +172,6 @@ extern uint8_t motd_len;
 
 extern uint16_t client_count;
 
-#pragma pack(push, 1)
-
 typedef struct {
   short x;
   short z;
@@ -181,6 +179,8 @@ typedef struct {
   uint8_t block;
 } BlockChange;
 
+#pragma pack(push, 1)
+
 typedef struct {
   uint8_t uuid[16];
   char name[16];