[scudo] Test ScudoReleaseTest.BufferPool with a buffer pool allocated on the heap

The previous code resulted in 252 KiB being allocated on the stack,
which caused a stack overflow on Fuchsia.

Reviewed By: Chia-hungDuan

Differential Revision: https://reviews.llvm.org/D146229

GitOrigin-RevId: 248ee65ac647ac53a415aea1cf314e82f5a30075
Change-Id: I1cf3a538acf9d82ff1f162834f131a2f23ef1b35
1 file changed