Look for bootanimation in apex-module

Look for bootanimation.zip in /apex/com.android.bootanimation/etc/.
This is needed to support download and install of customized bootanimations.

Bug: 116821733
Test:
1. Get a custom bootanimation.zip
2. Build a com.android.bootanimation.apex that contains the custom
   bootanimation.
3. Build a product partition containing the public avb-key in
   /product/etc/security/apex/ or a system partition containing the
   public avb-key in /system/product/etc/security/apex/
4. Flash the partition that was built.
5. $ adb install com.android.bootanimation.apex
6. $ adb reboot
7. Verify that the custom bootanimation is used during boot.

Change-Id: I0b63e8dd2ba536a5077e34f63670025f6e9d791a
diff --git a/cmds/bootanimation/BootAnimation.cpp b/cmds/bootanimation/BootAnimation.cpp
index 16af071..30f4ad4 100644
--- a/cmds/bootanimation/BootAnimation.cpp
+++ b/cmds/bootanimation/BootAnimation.cpp
@@ -69,6 +69,7 @@
 static const char PRODUCT_BOOTANIMATION_DARK_FILE[] = "/product/media/bootanimation-dark.zip";
 static const char PRODUCT_BOOTANIMATION_FILE[] = "/product/media/bootanimation.zip";
 static const char SYSTEM_BOOTANIMATION_FILE[] = "/system/media/bootanimation.zip";
+static const char APEX_BOOTANIMATION_FILE[] = "/apex/com.android.bootanimation/etc/bootanimation.zip";
 static const char PRODUCT_ENCRYPTED_BOOTANIMATION_FILE[] = "/product/media/bootanimation-encrypted.zip";
 static const char SYSTEM_ENCRYPTED_BOOTANIMATION_FILE[] = "/system/media/bootanimation-encrypted.zip";
 static const char OEM_SHUTDOWNANIMATION_FILE[] = "/oem/media/shutdownanimation.zip";
@@ -358,10 +359,10 @@
 
     const bool playDarkAnim = android::base::GetIntProperty("ro.boot.theme", 0) == 1;
     static const char* bootFiles[] =
-        {playDarkAnim ? PRODUCT_BOOTANIMATION_DARK_FILE : PRODUCT_BOOTANIMATION_FILE,
+        {APEX_BOOTANIMATION_FILE, playDarkAnim ? PRODUCT_BOOTANIMATION_DARK_FILE : PRODUCT_BOOTANIMATION_FILE,
          OEM_BOOTANIMATION_FILE, SYSTEM_BOOTANIMATION_FILE};
     static const char* shutdownFiles[] =
-        {PRODUCT_SHUTDOWNANIMATION_FILE, OEM_SHUTDOWNANIMATION_FILE, SYSTEM_SHUTDOWNANIMATION_FILE};
+        {PRODUCT_SHUTDOWNANIMATION_FILE, OEM_SHUTDOWNANIMATION_FILE, SYSTEM_SHUTDOWNANIMATION_FILE, ""};
 
     for (const char* f : (!mShuttingDown ? bootFiles : shutdownFiles)) {
         if (access(f, R_OK) == 0) {