You can provide the configure options using EXTRA_OECONF. Here, you can also append values to it based on your architecture.
EXTRA_OECONF_append_x86="--enable-x86"
EXTRA_OECONF_append_x64="--enable-x64"
You can do this only if your architecture (x86/x64) is defined as aprt of OVERRIDE value. Let us see what OVERRIDE value is:
The Yocto bitbake configuration values are defined in poky/meta/conf/bitbake.conf. In that file, there is a variable called OVERRIDE. The sample value for OVERRIDE in bitbake configuration is shown below:
OVERRIDES = "${TARGET_OS}:${TRANSLATED_TARGET_ARCH}:build-${BUILD_OS}:pn-${PN}:${MACHINEOVERRIDES}:${DISTROOVERRIDES}:${CLASSOVERRIDE}:forcevariable"
When you run bitbake -e and gather the output, the value for OVERRIDE translates into based on your configuration.
OVERRIDES="linux:i586:build-linux:pn-defaultpkgname:x86:qemuall:qemux86:poky:class-target:forcevariable:libc-glibc"
In your setup, if you can see x86/x64 as part of OVERRIDE value then you can define configure options as described earlier.