Mark functions as static

Mark functions used only in the same translation unit as static. This
only includes functions that do not have a prototype in a header file
either.

Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Closes #10470

module/os/linux/spl/spl-generic.c

@@ -543,7 +543,7 @@ spl_kernel_read(struct file *file, void *buf, size_t count, loff_t *pos)
 #endif
 }
 
-int
+static int
 spl_getattr(struct file *filp, struct kstat *stat)
 {
 	int rc;