This will help ASan find bugs in the translator when fuzzing, by making
separate allocations instead of using suballocations within the pool.

BUG=swiftshader:86

Change-Id: Ic59f7eef2c7985f7bf545d41be956df478331e2d
Reviewed-on: https://swiftshader-review.googlesource.com/13488Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Corentin Wallez <cwallez@google.com>