lib: reduce the use of module.h wherever possible

For files only using THIS_MODULE and/or EXPORT_SYMBOL, map
them onto including export.h -- or if the file isn't even
using those, then just delete the include.  Fix up any implicit
include dependencies that were being masked by module.h along
the way.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/lib/rational.c b/lib/rational.c
index 3ed247b..d326da3 100644
--- a/lib/rational.c
+++ b/lib/rational.c
@@ -7,7 +7,8 @@
  */
 
 #include <linux/rational.h>
-#include <linux/module.h>
+#include <linux/compiler.h>
+#include <linux/export.h>
 
 /*
  * calculate best rational approximation for a given fraction