pmb: add u-boot to native_cross_compile list (!1761)

This allows building u-boot much faster, previously it used to build
whole u-boot with distcc+qemu cross-compile, now it builds u-boot on
native chroot using cross-compilers.

pmb/config/__init__.py

@@ -164,7 +164,7 @@ build_packages = ["abuild", "build-base", "ccache"]
 
 # fnmatch for supported pkgnames, that can be directly compiled inside
 # the native chroot and a cross-compiler, without using distcc
-build_cross_native = ["linux-*", "arch-bin-masquerade"]
+build_cross_native = ["linux-*", "arch-bin-masquerade", "u-boot*"]
 
 # Necessary kernel config options
 necessary_kconfig_options = {