[compiler-rt] [scudo] change allocation buffer size with env var (PR #71703)

[Christopher Ferris via llvm-commits]

https://github.com/cferris1000 commented:

Is there any problem if this value is set negative or set to a really large positive value?

I want to make sure there is no possibility that a value here can cause a segfault.

https://github.com/llvm/llvm-project/pull/71703