I agree with Gaby, this looks great.
The testcases, however, might be improved by putting the check function
into testsuite_allocator.h: we try to avoid code duplication as much as
possible by moving test framework bits into the testsuite includes, as
inconceivable as it may seem. (And maybe name this common function
something more descriptive, like check_construct_destroy or whatever.)
You might want to consider naming the test files after whatever the
final function name is, instead of allocator1.cc. In addition, usually
we try to return zero from main, and use VERIFY or assert() to check
correctness.