Make one function inline

Signed-off-by: Gavin Howard <gavin@yzena.com>
diff --git a/src/num.c b/src/num.c
index a15297b..be9ee2e 100644
--- a/src/num.c
+++ b/src/num.c
@@ -130,7 +130,7 @@
  * @param n      The number to set to zero.
  * @param scale  The scale to set the number to.
  */
-static void
+static inline void
 bc_num_setToZero(BcNum* restrict n, size_t scale)
 {
 	assert(n != NULL);