um: Fix overlapping ELF segments when statically linked

When statically linked, the .text section in UML kernels is not page
aligned, causing it to share a page with the executable headers. As
.text and the executable headers have different permissions, this causes
the kernel to wish to map the same page twice (once as headers with r--
permissions, once as .text with r-x permissions), causing a segfault,
and a nasty message printed to the host kernel's dmesg:

"Uhuuh, elf segment at 0000000060000000 requested but the memory is
mapped already"

By aligning the .text to a page boundary (as in the dynamically linked
version in dyn.lds.S), there is no such overlap, and the kernel runs
correctly.

Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/kernel/uml.lds.S

@@ -19,10 +19,10 @@ SECTIONS
   __binary_start = START;
 
   . = START + SIZEOF_HEADERS;
+  . = ALIGN(PAGE_SIZE);
 
   _text = .;
   INIT_TEXT_SECTION(0)
-  . = ALIGN(PAGE_SIZE);
 
   .text      :
   {