contrib: Make X=Y arguments work in install_db4

Trailing X=Y arguments are supposed to be passed through unchanged
to bdb's configure. This was not the case, at least with OpenBSD
6.2's shell.

Fix this by not storing the arguments in a temporary variable but
passing "$@" through directly.

contrib/install_db4.sh

@@ -17,7 +17,6 @@ expand_path() {
 }
 
 BDB_PREFIX="$(expand_path ${1})/db4"; shift;
-BDB_EXTRA_CONFIGURE_FLAGS="${@}"
 BDB_VERSION='db-4.8.30.NC'
 BDB_HASH='12edc0df75bf9abd7f82f821795bcee50f42cb2e5f76a6a281b85732798364ef'
 BDB_URL="https://download.oracle.com/berkeley-db/${BDB_VERSION}.tar.gz"
@@ -70,7 +69,7 @@ cd build_unix/
 
 "${BDB_PREFIX}/${BDB_VERSION}/dist/configure" \
   --enable-cxx --disable-shared --with-pic --prefix="${BDB_PREFIX}" \
-  "${BDB_EXTRA_CONFIGURE_FLAGS}"
+  "${@}"
 
 make install