Description:
Programs directly using kernel headers cannot be compiled using the musl-gcc wrapper.
This can easily be fixed by adding something like this to the end of the package()-function in the PKGBUILD:

for i in linux asm asm-generic; do
ln -s /usr/include/$i "$pkgdir/usr/lib/musl/include/$i"
done

Additional info:
* Missing in version 1.1.5-1

Steps to reproduce:

$ cat > test.c <<EOF
#include <linux/dm-ioctl.h>

int main() {
return 42;
}
EOF

$ musl-gcc test.c -o test