Cleanup programs further

removed casting of main args to void
diff --git a/programs/pkey/key_app.c b/programs/pkey/key_app.c
index f89f436..7c01caf 100644
--- a/programs/pkey/key_app.c
+++ b/programs/pkey/key_app.c
@@ -64,11 +64,8 @@
 
 #if !defined(POLARSSL_BIGNUM_C) ||                                  \
     !defined(POLARSSL_PK_PARSE_C) || !defined(POLARSSL_FS_IO)
-int main( int argc, char *argv[] )
+int main( void )
 {
-    ((void) argc);
-    ((void) argv);
-
     polarssl_printf("POLARSSL_BIGNUM_C and/or "
            "POLARSSL_PK_PARSE_C and/or POLARSSL_FS_IO not defined.\n");
     return( 0 );