If musl.dl.debug.dlclose is enabled, the sections of dlclosed library will not be unmapped.
Instead the mmap area will be set to PROT_NONE. If the program run into the dlclosed library
the crash log would contain the library info rather than a unmapped pc.
The param can be set by following cmdline:
param set musl.dl.debug.dlclose enable

Issue: I69Y3Z
Test: backtrace_local_test
Signed-off-by: NMapleStory <zengzhi5@huawei.com>