But keep use of cmake idiomatic way of making inlines hidden

Something weird seems to be going on. Just kill it.

Fixes https://github.com/harfbuzz/harfbuzz/issues/888

They are handled in our common header.

Bad bad bad bad code. Don't do that. If compiler's not happy, understand why.

This reverts commit b9dcbb1f.

This is gross. Should be only done if a specific macro is defined. Not the other way
around. This fails my build as autotools companions where not added anyway.

CMake: hide symbols by default on non-MSVC, define export attribute

This covers all built libraries now and both static and shared builds.

This change makes sure that non-MSVC builds using CMake properly hide
non-exported functions.

Fix CMake builds on Windows, MSVC in particular

Put in the utility program that was missed in installation by replacing
the one that was duplicated.

The list of source files to pass to g-ir-scanner is becoming too
long for Windows, as Windows imposes a 8192-character limit for command
lines, so we need to first transform that list into a listings file, and
then use the --filelist option for g-ir-scanner to build the
introspection files.

Include stdbool.h in hb-setset-test.h instead of in the individual
sources, if it is found; otherwise use a simplistic fallback for it if
it is not found.

Also declare variables at the top of the block, to build on pre-C99
compiliers.

For the API tests, output the test programs at $(TOP_BUILDDIR) so that
the freshly-built DLLs will be available for the test programs.  For
those that are run through the Python wrapper scripts, use
${PYTHON_EXECUTABLE} instead of plain 'python' in case the Python
interpreter is not in the PATH.

Add a simplistic round() implementation for our purposes, used when the
compiler does not support round() directly.

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.