lib/, tests/: addsl2(): Rename addsl() to addsl2()

This is for consistency with addsl3(), and in preparation for the
following commit, which will unify the interface into a single addsl()
macro.

Signed-off-by: Alejandro Colomar <alx@kernel.org>

lib/adds.c

@@ -7,7 +7,7 @@
 #include "adds.h"
 
 
-extern inline long addsl(long a, long b);
+extern inline long addsl2(long a, long b);
 extern inline long addsl3(long a, long b, long c);
 
 extern inline int cmpl(const void *p1, const void *p2);

lib/adds.h

@@ -15,14 +15,14 @@
 #include "sizeof.h"
 
 
-inline long addsl(long a, long b);
+inline long addsl2(long a, long b);
 inline long addsl3(long a, long b, long c);
 
 inline int cmpl(const void *p1, const void *p2);
 
 
 inline long
-addsl(long a, long b)
+addsl2(long a, long b)
 {
 	if (a > 0 && b > LONG_MAX - a) {
 		errno = EOVERFLOW;