Basic static analysis fixes

- remove extraneous semicolons
- use "nullptr" instead of "0"
- remove "break" after "return"
- use <cstdio> instead of <stdio.h>

include/godot_cpp/templates/cowdata.hpp

@@ -190,7 +190,7 @@ public:
 
 	_FORCE_INLINE_ CowData() {}
 	_FORCE_INLINE_ ~CowData();
-	_FORCE_INLINE_ CowData(CowData<T> &p_from) { _ref(p_from); };
+	_FORCE_INLINE_ CowData(CowData<T> &p_from) { _ref(p_from); }
 };
 
 template <class T>

include/godot_cpp/templates/hashfuncs.hpp

@@ -228,7 +228,7 @@ static _FORCE_INLINE_ uint32_t hash_murmur3_buffer(const void *key, int length,
 			k1 = hash_rotl32(k1, 15);
 			k1 *= c2;
 			h1 ^= k1;
-	};
+	}
 
 	// Finalize with additional bit mixing.
 	h1 ^= length;

include/godot_cpp/templates/rb_set.hpp

@@ -77,7 +77,7 @@ public:
 		}
 		const T &get() const {
 			return value;
-		};
+		}
 		Element() {}
 	};
 

include/godot_cpp/templates/rid_owner.hpp

@@ -37,7 +37,7 @@
 #include <godot_cpp/templates/spin_lock.hpp>
 #include <godot_cpp/variant/utility_functions.hpp>
 
-#include <stdio.h>
+#include <cstdio>
 #include <typeinfo>
 
 namespace godot {