Fix Mac build and make -jN use a total of N threads, not N+1.

Change-Id: I41dc613e76d6ac85a21b3286b1a555dcc79bae95
diff --git a/src/runtime_support.cc b/src/runtime_support.cc
index f9f3d07..b68f7ac 100644
--- a/src/runtime_support.cc
+++ b/src/runtime_support.cc
@@ -494,7 +494,7 @@
     if (UNLIKELY(fh.IsPrimitiveType() != is_primitive ||
                  fh.FieldSize() != expected_size)) {
       self->ThrowNewExceptionF("Ljava/lang/NoSuchFieldError;",
-                               "Attempted read of %d-bit %s on field '%s'",
+                               "Attempted read of %zd-bit %s on field '%s'",
                                expected_size * (32 / sizeof(int32_t)),
                                is_primitive ? "primitive" : "non-primitive",
                                PrettyField(resolved_field, true).c_str());