uml: sigprocmask fix

[Shane Hathaway <shane@hathawaymix.org>]

I just ran into the same issue described here:

http://lkml.org/lkml/2009/1/15/194

Like Americo Wang, my user mode linux compile failed when attempting to
link ".tmp_vmlinux".  However, his patch is probably wrong.  The problem
is that the name "sigprocmask" is getting renamed to
"kernel_sigprocmask" by a compiler directive in arch/um/Makefile, then
that name gets mangled into "sys_kernel_sigprocmask" by the
SYSCALL_DEFINE3(sigprocmask, ...) macro in kernel/signal.c.

So I added the following line to arch/um/sys-i386/sys_call_table.S:

#define sys_sigprocmask sys_kernel_sigprocmask

This made it compile and link correctly.  Look at the symbols generated
by the compile of signal.c to see what I mean:

# nm kernel/signal.o | grep sigprocmask
0000008f r __kstrtab_kernel_sigprocmask
00000040 r __ksymtab_kernel_sigprocmask
00001ea6 T kernel_sigprocmask
00002d67 T sys_kernel_sigprocmask
00001faf T sys_rt_sigprocmask

Unfortunately, it's a mystery to me that others haven't run into this
before.

Shane