rwengine: check whether character is player

Fixes rwengine#519

==13884==ERROR: AddressSanitizer: heap-use-after-free on address 0x607000b3d954 at pc 0x0000008ba469 bp 0x7ffd7c8f9ab0 sp 0x7ffd7c8f9aa0
READ of size 4 at 0x607000b3d954 thread T0
    #0 0x8ba468 in PlayerController::isTalkingOnPayphone() const /home/maarten/programming/openrw/rwengine/src/ai/PlayerController.cpp:315
    #1 0xa148eb in CharacterObject::updateMovementAnimation(float) /home/maarten/programming/openrw/rwengine/src/objects/CharacterObject.cpp:128
    #2 0xa185d9 in CharacterObject::updateCharacter(float) /home/maarten/programming/openrw/rwengine/src/objects/CharacterObject.cpp:356
    rwengine#3 0xa17735 in CharacterObject::tick(float) /home/maarten/programming/openrw/rwengine/src/objects/CharacterObject.cpp:297
    rwengine#4 0x7c7731 in RWGame::tick(float) /home/maarten/programming/openrw/rwgame/RWGame.cpp:541
    rwengine#5 0x7c6abb in RWGame::run() /home/maarten/programming/openrw/rwgame/RWGame.cpp:447
    rwengine#6 0x793b45 in main /home/maarten/programming/openrw/rwgame/main.cpp:17
    rwengine#7 0x7f154c17e18a in __libc_start_main (/lib64/libc.so.6+0x2318a)
    rwengine#8 0x793839 in _start (/home/maarten/programming/openrw/build/build/rwgame/rwgame+0x793839)

rwengine/src/objects/CharacterObject.cpp

@@ -122,7 +122,7 @@ void CharacterObject::destroyActor() {
 glm::vec3 CharacterObject::updateMovementAnimation(float dt) {
     glm::vec3 animTranslate{};
 
-    if (controller) {
+    if (isPlayer()) {
         auto c = static_cast<PlayerController*>(controller);
 
         if (c->isTalkingOnPayphone()) {