Add malloc benchmarks.

Adding some benchmarks that keep a certain number of allocation
around. This benchmark should not be used as an absolute for determining
what is a good/bad native allocator. However, it should be used to make
sure that numbers are not completely changed between allocator versions.

Also update the malloc sql benchmark to match the same style as these
new benchmarks.

Bug: 129743239

Test: Ran these benchmarks.
Change-Id: I1995d98fd269b61d9c96efed6eff3ed278e24c97
Merged-In: I1995d98fd269b61d9c96efed6eff3ed278e24c97
(cherry picked from commit 7ec2c8a9b6f9a050d2ac9e0c35f0a631573f3de6)