Silence some warnings when building on Mac

The *-clang* selector doesn't appear to work correctly in my build environment
(or I just don't understand how it is supposed to work). Either way, making
this conditional on !mac works.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/planner.c b/planner.c
index 5ef66961b..cdc13a599 100644
--- a/planner.c
+++ b/planner.c
@@ -268,7 +268,7 @@ struct dive *create_dive_from_plan(struct diveplan *diveplan, const char **error
 			int plano2 = (o2 + 5) / 10 * 10;
 			int planhe = (he + 5) / 10 * 10;
 			int idx;
-			if (idx = add_gas(dive, plano2, planhe) < 0)
+            if ((idx = add_gas(dive, plano2, planhe)) < 0)
 				goto gas_error_exit;
 			add_gas_switch_event(dive, dc, lasttime, idx);
 			oldo2 = o2; oldhe = he;