[sanitizer] Change SizeClassAllocator32 to accept just one template

Summary:
With rL279771, SizeClassAllocator64 was changed to accept only one template
instead of 5, for the following reasons: "First, this will make the mangled
names shorter. Second, this will make adding more parameters simpler". This
patch mirrors that work for SizeClassAllocator32.

This is in preparation for introducing the randomization of chunks in the
32-bit SizeClassAllocator in a later patch.

Reviewers: kcc, alekseyshl, dvyukov

Reviewed By: alekseyshl

Subscribers: llvm-commits, kubamracek

Differential Revision: https://reviews.llvm.org/D33141

llvm-svn: 303071