I get build error which complains that include/uapi/asm-generic/auxvec.h is
missing although the file exists. I'm using gcc 3.3.5.
This bug seems to not happen with gcc 4.x.

# make
make[1]: Nothing to be done for `all'.
make[1]: Nothing to be done for `relocs'.
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
  CALL    scripts/checksyscalls.sh
  CHK     include/generated/compile.h
make[3]: `arch/x86/realmode/rm/realmode.bin' is up to date.
  CHK     include/generated/uapi/linux/version.h
make[2]: Nothing to be done for `all'.
make[2]: Nothing to be done for `relocs'.
/usr/src/all/linux/scripts/Makefile.headersinst:50: *** Missing UAPI file /usr/src/all/linux/include/uapi/asm-generic/auxvec.h.  Stop.
make[2]: *** [asm-generic] Error 2
make[1]: *** [headers_install] Error 2
make: *** [vmlinux] Error 2
# ls -l /usr/src/all/linux/include/uapi/asm-generic/auxvec.h
-rw-r--r--  1 root root 218 Oct 20 14:56 /usr/src/all/linux/include/uapi/asm-generic/auxvec.h

Linux 3.6 builds fine. I can't use "git bisect" until Linux 3.7-rc6 but
possibly caused by either commit 10b63956 "UAPI: Plumb the UAPI Kbuilds into
the user header installation and checking" or commit 40f1d4c2 "UAPI: Remove the
objhdr-y export list".