Introduce a new macro, CRYB_I_AM, which replaces CRYB_INIT for projects that provide Cryb components or extensions. Currently, the main difference is that they are not required to have the exact same PACKAGE_VERSION as the Cryb version that they use.
Most importantly, differentiate between library and non-library components. The former can be provided and required, and if provided but disabled, can be replaced by pre-installed versions. The latter can only be provided and cannot be the target of a dependency relationship.
The caveat is needed because if you include one of these headers on a system that defines rsize_t without having the correct incantations in your configure.ac, you are going to have a bad time. But there is no good general solution to the problem.
These macros are designed to work in concert with the AX_PKG_CONFIG macros. It is now possible to disable any component, even if another depends on it, provided that it is already installed. For enabled components, we define the same variables as AX_PKG_CONFIG would, so Makefiles don't need to know if a component they rely on is being built as part of this packge or if it was already installed.
This is the default if the AM_MAINTAINER_MODE macro is not invoked, but invoking it also creates the --disable-maintainer-mode option which some automated build tools use to speed up builds from a clean tree.
Travis forces _FORTIFY_SOURCE, which enables warn_unused_result annotations in glibc. Some of those annotations are of dubious value; in the case of asprintf(3) and vasprintf(3), they flag code that doesn't check the return value as unsafe even if it checks the pointer instead (which is guaranteed to be NULL in case of failure, and arguably more useful than the return value). Unfortunately, gcc intentionally ignores (void) casts, so we have no choice but to quench the warning with -Wno-unused-result. However, some of the compilers we wish to support don't recognize it, so we move it from the developer flags to the Travis environment.
While there, switch Travis from Precious to Trusty.
Unlike assert(3), which uses abort(3), this has no other side effects (before raising SIGABRT) than an fprintf() call. The test framework will catch the SIGABRT, report that the test case failed, and proceed with the next case.
It does not seem that gcc accepts casting to void as an alternative to actually checking the result. The only recourse we have is to disable the warning.
a caller-provided buffer. Use it to warn about leaks in each individual
test case. Note that we can't fail a test case for leaking, because
individual test cases in a unit may modify shared state which is cleaned
up at the end of the series.
