kbuild: Do not unnecessarily regenerate modules.builtin
kbuild: Do not unnecessarily regenerate modules.builtin

Only regenerate it if the configuration has changed. Also, do this after
the modules build to fix errors with some weird Makefiles that are
generated during build.

Reported-by: Eric Miao <60e376623d7bcedd53f4c51cbb2c060fb40a4887@gmail.com>
Signed-off-by: Michal Marek <0c835876a532a476f30fdb1f6e963bae6c5a1a04@suse.cz>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs