hle/result: Declare copy/move constructor/assignment as noexcept

While we're at it, we can also declare these copy/move constructor/assignment as noexcept.

src/core/hle/result.h

@@ -206,7 +206,7 @@ public:
         return result;
     }
 
-    ResultVal(const ResultVal& o) : result_code(o.result_code) {
+    ResultVal(const ResultVal& o) noexcept : result_code(o.result_code) {
         if (!o.empty()) {
             new (&object) T(o.object);
         }
@@ -224,7 +224,7 @@ public:
         }
     }
 
-    ResultVal& operator=(const ResultVal& o) {
+    ResultVal& operator=(const ResultVal& o) noexcept {
         if (this == &o) {
             return *this;
         }
@@ -244,7 +244,7 @@ public:
         return *this;
     }
 
-    ResultVal& operator=(ResultVal&& o) {
+    ResultVal& operator=(ResultVal&& o) noexcept {
         if (this == &o) {
             return *this;
         }