cppcheck 1.89 enabled certain value flow analysis mechanisms [1] which
trigger null pointer dereference false positives that were previously
not reported. It seems that cppcheck no longer treats at least some
REQUIRE() assertion failures as fatal, so add extra assertion macro
definitions to lib/isc/include/isc/util.h that are only used when the
CPPCHECK preprocessor macro is defined; these definitions make cppcheck
1.89 behave as expected.
There is an important requirement for these custom definitions to work:
cppcheck must properly treat abort() as a function which does not
return. In order for that to happen, the __GNUC__ macro must be set to
a high enough number (because system include directories are used and
system headers compile attributes away if __GNUC__ is not high enough).
__GNUC__ is thus set to the major version number of the GCC compiler
used, which is what that latter does itself during compilation.
[1] aaeec462e6
(cherry picked from commit abfde3d543)
ae7c0cca89