add -c to /bin/sh

auto/feature

diff --git a/auto/feature b/auto/feature
index afe171c..0cf1f1e 100644
--- a/auto/feature
+++ b/auto/feature
@@ -44,7 +44,7 @@
 
         yes)
             # /bin/sh is used to intercept "Killed" or "Abort trap" messages
-            if /bin/sh $NGX_AUTOTEST >/dev/null 2>&1; then
+            if /bin/sh -c $NGX_AUTOTEST >/dev/null 2>&1; then
                 echo " found"
                 ngx_found=yes
 
@@ -59,7 +59,7 @@
 
         bug)
             # /bin/sh is used to intercept "Killed" or "Abort trap" messages
-            if /bin/sh $NGX_AUTOTEST >/dev/null 2>&1; then
+            if /bin/sh -c $NGX_AUTOTEST >/dev/null 2>&1; then
                 echo " not found"
 
             else