Remove unnecessary explicit includes (#16)

src/frontend/ir/ir_emitter.cpp

@@ -5,7 +5,8 @@
  */
 
 #include "common/assert.h"
-#include "ir_emitter.h"
+#include "frontend/ir/ir_emitter.h"
+#include "frontend/ir/opcodes.h"
 
 namespace Dynarmic {
 namespace IR {

src/frontend/ir/ir_emitter.h

@@ -11,7 +11,6 @@
 #include "common/common_types.h"
 #include "frontend/arm_types.h"
 #include "frontend/ir/basic_block.h"
-#include "frontend/ir/opcodes.h"
 #include "frontend/ir/terminal.h"
 #include "frontend/ir/value.h"
 
@@ -25,6 +24,8 @@
 namespace Dynarmic {
 namespace IR {
 
+enum class Opcode;
+
 /**
  * Convenience class to construct a basic block of the intermediate representation.
  * `block` is the resulting block.