x86: convert almost generic headers to asm-generic version

In x86, mman.h, module.h, scatterlist.h, types.h and ucontext.h
can use the asm-generic version by just defining the x86
specific parts locally and falling back on the generic code
for the common bits.

This patch illustrates the differences between the x86 and
asm-generic versions by changing a file that is initially
identical to the x86 version to one that is identical
to the asm-generic version.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
LKML-Reference: <cover.1245354003.git.arnd@arndb.de>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>