An enum is initialized as zero if it doesn't have default value

In C++, NDK backend, an enum value hasn't been initialized if it doesn't
have default value. In that case, initialize an enum with zero for the
backends.

Bug: 198346478
Test: check golden output and m
Ignore-AOSP-First: security patch
Change-Id: I6cb67258cc4aacc41ae80c46ccee10a3cfe723f6
Merged-In: I6cb67258cc4aacc41ae80c46ccee10a3cfe723f6
(cherry picked from commit f39b16442ad832f2921ad0eec298b7c333936dc1)
2 files changed