build: disable -Wself-assign
build: disable -Wself-assign

Prevent these warnings in clang 3.6:

    ./serialize.h:96:9: warning: explicitly assigning value of variable of type 'uint64_t' (aka 'unsigned long') to itself [-Wself-assign]
        obj = (obj);
        ~~~ ^  ~~~

bitcoinxt/bitcoinxt,bitcoinxt/bitcoinxt,bitcoinxt/bitcoinxt,dagurval/bitcoinxt,dagurval/bitcoinxt,bitcoinxt/bitcoinxt,dagurval/bitcoinxt,dagurval/bitcoinxt,bitcoinxt/bitcoinxt,bitcoinxt/bitcoinxt,dagurval/bitcoinxt,dagurval/bitcoinxt