configure: Check for SecItemImport for securetransport as well

This fixes the default build on iOS; eventually I should come up with
a better solution for that platform.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

configure

@@ -5218,7 +5218,7 @@ fi
 enabled sdl && add_cflags $sdl_cflags && add_extralibs $sdl_libs
 
 disabled securetransport || { check_func SecIdentityCreate "-Wl,-framework,CoreFoundation -Wl,-framework,Security" &&
-    check_lib2 Security/SecureTransport.h SSLCreateContext "-Wl,-framework,CoreFoundation -Wl,-framework,Security" &&
+    check_lib2 "Security/SecureTransport.h Security/Security.h" "SSLCreateContext SecItemImport" "-Wl,-framework,CoreFoundation -Wl,-framework,Security" &&
     enable securetransport; }
 
 makeinfo --version > /dev/null 2>&1 && enable makeinfo  || disable makeinfo