Separate the module source and header checksum into a separate modinfo
field srcversion.

With CONFIG_MODULE_SRCVERSION_ALL=y, put srcversion into every module, not
just those with MODULE_VERSION("something").

Patch by Rusty Russell, trivial merging and testing by Matt Domsch
Signed-off-by: Matt Domsch <Matt_Domsch@dell.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>