python3.4: fix musl builds.

srcpkgs/python3.4/template

@@ -26,6 +26,7 @@ pre_configure() {
 }
 
 do_configure() {
+	local _args
 	unset GCC CC CXX CPP LD AR AS RANLIB
 	if [ "$CROSS_BUILD" ]; then
 		mkdir -p host-build
@@ -36,8 +37,9 @@ do_configure() {
 		mv python ../hostpython
 		cd ..
 		patch -Np0 -i ${FILESDIR}/cross.patch
+		_args="--build=${XBPS_MACHINE%%-musl}"
 	fi
-	./configure ${configure_args} --build=${XBPS_MACHINE}-unknown-linux-gnu \
+	./configure ${configure_args} ${_args} \
 		--with-threads --enable-ipv6 --with-signal-module \
 		--with-system-ffi --with-system-expat \
 		--enable-shared --without-ensurepip \