Summary:
This avoids warnings about e.g., sizeof(k++) that result
from macro expansion.
* folly/futures/test/ExecutorTest.cpp: Move increment out
of macro argument list.
* folly/test/FBVectorTestBenchmarks.cpp.h: Likewise.
* folly/test/LazyTest.cpp: Likewise.
Otherwise, we'd get errors like this:

folly/test/LazyTest.cpp:49:118: error: expression with side effects has no effect in an unevaluated context [-Werror,-Wunevaluated-expression]
switch (0) case 0: default: if (const ::testing::AssertionResult gtest_ar = (::testing::internal:: EqHelper<(sizeof(::testing::internal::IsNullLiteralHelper(++globalCount())) == 1)>::Compare("++globalCount()", "1", ++globalCount(), 1))) ; else ::testing::internal::AssertHelper(::testing::TestPartResult::kNonFatalFailure, "folly/test/LazyTest.cpp", 49, gtest_ar.failure_message()) = ::testing::Message();
^

Test Plan:
Run these commands and note there are fewer errors than before:
fbconfig --clang --with-project-version=clang:dev -r folly && fbmake dbgo

Reviewed By: njormrod@fb.com

Subscribers: folly-diffs@, jsedgwick, yfeldblum

FB internal diff: D1848324

Tasks: 6244745

Signature: t1:1848324:1423860890:bce44c5e0895804a21957893ae6b78e76dfbc4d3