Fix the reexec-insert-libraries-env.cc testcase to use %env to make it work on iOS simulator.
// RUN: -dynamiclib -o darwin-dummy-shared-lib-so.dylib
// FIXME: the following command line may hang in the case of a regression.
-// RUN: env DYLD_INSERT_LIBRARIES=darwin-dummy-shared-lib-so.dylib \
+// RUN: %env DYLD_INSERT_LIBRARIES=darwin-dummy-shared-lib-so.dylib \
// RUN: %run %t 2>&1 | FileCheck %s || exit 1
#if !defined(SHARED_LIB)
