Revert "arm: fix location of some include files"

This reverts commit e1f555ced0ddc4033c9b7fb122071acbdf29a590.
Revert "Add linux-headers to QEMU_INCLUDES"

This reverts commit 218d42ec53fa218c25b04a2d1f4e3c81375b03b3.
Revert "Fix failure to create q35 machine"

This reverts commit a96b2611c52e0edd07812a4d0d64b686f5c7e58e.
Revert "hw: Add lost ARM core again"

This reverts commit f367c0b740732f85a188922a1bad11439729ca81.
Revert "acpi: move declarations from pc.h to acpi.h"

This reverts commit 6e6ab35bd2ccf1c88eb3772da7518beaa398a1df.