uml: syle fixes in arch/um/os-Linux

Style fixes in arch/um/os-Linux/irq.c and arch/um/os-Linux/sigio.c:
	Updated copyrights
	trimmed includes
	added severity indicators to printks
	CodingStyle fixes
	turned an bunch of panics into printks
	call some libc functions directly instead of going through the
os_* wrappers

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>