Do not rely on compiler and check boundaries

C++ considers the overflow of a signed integer to be an undefined behavior (even with the "Signed Integers are Two's Complement" update: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0907r1.html ).

Instead of relying on tests(1) to discover if a compiler does not handle the signed integer overflow as we expect it to, we should add an explicit check before incrementing.

(1) See
thrift/lib/cpp/src/thrift/async/TConcurrentClientSyncInfo.cpp

Lines 33 to 34 in c4e899a

Quick check on https://godbolt.org/z/d7W8ds shows that Clang is able to optimize and just do the +1 so modern compilers should be able to keep the same performances where hardware permits.

In addition, some company rules might require code to do just that:
https://wiki.sei.cmu.edu/confluence/display/c/INT32-C.+Ensure+that+operations+on+signed+integers+do+not+result+in+overflow