CDRIVER-4237 - Address incompatible pointer warnings on GCC 4.8.5

[eramongodb]

This PR aims to resolve CDRIVER-4237, depended on by PHP-2013.

Four Three types of warnings are addressed by this PR (as described by GCC 4.8.5):

• ISO C does not allow extra ; outside of a function [-Wpedantic]
• passing argument {N} of {func} from incompatible pointer type [enabled by default]
• pointer targets in passing argument {N} of {func} differ in signedness [-Wpointer-sign]
• empty macro arguments are undefined in ISO C90 and ISO C++98 [enabled by default]

Followup changes in addition to the current set may need to be added to fully resolve PHPC-2013. These will be added as demanded in response to code review.

[eramongodb]

Reverted "fixes" to empty macro arguments that were not sufficiently tested for correctness.

[vector-of-bool]

The changes look simple enough. Is it really that the compilers mishandle typedefs for their intrinsics? That surprises me.

My only question is about formatting: The prior (wonky) formatting came from my clang-format frantically trying to enforce the 80 column limit (which is much too small, imo), so the the prior formatting satisfied the .clang-format in the repository. What version of clang-format are you using? Or did you do some other formatting formatting?

[kevinAlbs]

Thank you for the fix. The current changes LGTM. Please re-request review if there are followup changes.

[eramongodb]

What version of clang-format are you using? Or did you do some other formatting formatting?

@vector-of-bool I am using .clang-format as provided by the C driver repository. Normally I use the clang-format executable as provided via VS Code's C/C++ extension. Running the system clang-format executable (clang version 10.0.0-4ubuntu1) from project root with the command clang-format --style=file -i src/libbson/src/bson/bson-atomic.h yields the same result.

[jmikola]

This patch fixed PHP builds on zSeries. PPC is still failing for unrelated reasons (tasks), but I've noted the successful PPC builds for libmongoc (tasks) so I have no objections to merging.