vpx_dec_fuzzer: Remove dependency on tools_common.c

Instead of calling get_vpx_decoder_by_name(), derive
decoder interface directly.

This will avoid dependecy on tools_common and hence any potential
updates needed to build fuzzer, when tools_common uses functions
defined in a different file

With this dependency removed, fuzzer no longer needs to enable examples
when building vpx_dec_fuzzer binaries

Change-Id: I05753edf041b4bc742a6dc06e809a8a2929d379f
1 file changed