inputflinger: Check for KeyCharacterMap before use

Fixes crash in InputReader:

10-09 23:27:30.342 F DEBUG   : pid: 2243, tid: 2413, name: InputReader  >>> system_server <<<
10-09 23:27:30.342 F DEBUG   : uid: 1000
10-09 23:27:30.342 F DEBUG   : tagged_addr_ctrl: 0000000000000001 (PR_TAGGED_ADDR_ENABLE)
10-09 23:27:30.342 F DEBUG   : signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x0000000000000040
10-09 23:27:30.342 F DEBUG   : Cause: null pointer dereference

Bug: 372558955
Test: Does not crash on input device without character map
Flag: EXEMPT bugfix
Change-Id: I0f4ada4663bdd51a233fa9c15eb2558db0081dd5

Author: SikkaTheCoder

services/inputflinger/reader/EventHub.cpp

@@ -662,8 +662,12 @@ bool EventHub::Device::hasKeycodeLocked(int keycode) const {
     if (hasKeycodeInternalLocked(keycode)) {
         return true;
     }
-
-    for (auto& fromKey : getKeyCharacterMap()->findKeyCodesMappedToKeyCode(keycode)) {
+    // Check the key character map first. Not all input devices will have one.
+    const std::shared_ptr<KeyCharacterMap> kcm = getKeyCharacterMap();
+    if (kcm == nullptr) {
+        return false;
+    }
+    for (auto& fromKey : kcm->findKeyCodesMappedToKeyCode(keycode)) {
         if (hasKeycodeInternalLocked(fromKey)) {
             return true;
         }