configure.ac/CMake: Check for round() and stdbool.h

Not all the compilers that HarfBuzz is buildable on supports round() and
has the header stdbool.h, so we check for them and define HAVE_ROUND and
HAVE_STDBOOL_H repsectively in our CFLAGS so that we include them only
when they are found, or use fallback implementations when necessary.

Also include FindPythonInterp earlier as we need PYTHON_EXECUTABLE to be
set for running the tests.
2 files changed