Remove __linux__ ifdefs where not needed

The downstream branches now know about Parcel and binder, so in some
places, these #ifdef statements are not needed.

This CL should help reduce the divergence with downstream efforts. See
the merge conflict resolution CL as an example:
https://googleplex-android-review.git.corp.google.com/c/platform/frameworks/native/+/27201796/-2..3

Bug: 309829647
Test: presubmit
Change-Id: Iec17cface5069ca79a565c205546db8ada8a07ee
diff --git a/libs/input/KeyCharacterMap.cpp b/libs/input/KeyCharacterMap.cpp
index 41909bf..f75bf41 100644
--- a/libs/input/KeyCharacterMap.cpp
+++ b/libs/input/KeyCharacterMap.cpp
@@ -19,11 +19,9 @@
 #include <stdlib.h>
 #include <string.h>
 
-#ifdef __linux__
-#include <binder/Parcel.h>
-#endif
 #include <android/keycodes.h>
 #include <attestation/HmacKeyManager.h>
+#include <binder/Parcel.h>
 #include <input/InputEventLabels.h>
 #include <input/KeyCharacterMap.h>
 #include <input/Keyboard.h>
@@ -611,7 +609,6 @@
     }
 }
 
-#ifdef __linux__
 std::unique_ptr<KeyCharacterMap> KeyCharacterMap::readFromParcel(Parcel* parcel) {
     if (parcel == nullptr) {
         ALOGE("%s: Null parcel", __func__);
@@ -744,7 +741,6 @@
         parcel->writeInt32(toAndroidKeyCode);
     }
 }
-#endif // __linux__
 
 // --- KeyCharacterMap::Parser ---