build: if VERSION_BUILD is non-zero, include it in the package version

When the build number (CLIENT_VERSION_BUILD) is non-zero, we want
to include that in the package version number so the resulting binaries
are named with the correct version.

Author: achow101

configure.ac

@@ -8,7 +8,7 @@ define(_CLIENT_VERSION_IS_RELEASE, false)
 define(_COPYRIGHT_YEAR, 2018)
 define(_COPYRIGHT_HOLDERS,[The %s developers])
 define(_COPYRIGHT_HOLDERS_SUBSTITUTION,[[Bitcoin Core]])
-AC_INIT([Bitcoin Core],[_CLIENT_VERSION_MAJOR._CLIENT_VERSION_MINOR._CLIENT_VERSION_REVISION],[https://github.com/bitcoin/bitcoin/issues],[bitcoin],[https://bitcoincore.org/])
+AC_INIT([Bitcoin Core],m4_join([.], _CLIENT_VERSION_MAJOR, _CLIENT_VERSION_MINOR, _CLIENT_VERSION_REVISION, m4_if(_CLIENT_VERSION_BUILD, [0], [], _CLIENT_VERSION_BUILD)),[https://github.com/bitcoin/bitcoin/issues],[bitcoin],[https://bitcoincore.org/])
 AC_CONFIG_SRCDIR([src/validation.cpp])
 AC_CONFIG_HEADERS([src/config/bitcoin-config.h])
 AC_CONFIG_AUX_DIR([build-aux])