Configurations/15-android.conf: fix implicit __ANDROID_API__ handling.
03ad7c00 failed if one didn't pass explicit -D__ANDROID_API__=N :-( Reviewed-by:Matt Caswell <matt@openssl.org> Reviewed-by:
Richard Levitte <levitte@openssl.org> (Merged from https://github.com/openssl/openssl/pull/7443)