Load preinstalled sytem font if fs-verity is not supported

Some form factor doesn't support fs-verity and it ends up with NPE
during boot because of empty system font map.
To work on such environment, load preinstalled system font before
serializing system font map.

Bug: N/A
Test: N/A
Change-Id: Ibc4d512e1a70d9e7be889ea7b1e6afa5e45b1bbb

services/core/java/com/android/server/graphics/fonts/FontManagerService.java

@@ -269,6 +269,9 @@ public final class FontManagerService extends IFontManager.Stub {
         synchronized (mUpdatableFontDirLock) {
             mUpdatableFontDir = createUpdatableFontDir();
             if (mUpdatableFontDir == null) {
+                // If fs-verity is not supported, load preinstalled system font map and use it for
+                // all apps.
+                Typeface.loadPreinstalledSystemFontMap();
                 setSerializedFontMap(serializeSystemServerFontMap());
                 return;
             }