bugs: Various new bugs for small features
gvariant: Explicitly use fixed-width GLib types in error messages

Otherwise we can end up with error messages which recommend using a C
standard ‘long’, whose width varies between architectures. Using that is
a bad idea.
gvariant: Check for use of architecture-dependent types

If the user passes an architecture-dependent type into a GVariant
variadic function, the behaviour will differ between architectures,
which we really do not want — essentially the code would be using the
wrong width integer on one architecture but not another, which would be
hard to track down. This is mostly a problem with ‘long’, which is 32
bits wide on 32-bit systems, and 64 bits wide on 64-bit systems.

This was a problem encountered in the wild in telepathy-gabble. Thanks
to Simon McVittie for suggesting that Tartan check for it.
gvariant: Use Clang’s internal handling of integer promotion

Rather than reinventing it ourselves. This is not a behavioural change.
gir-manager: Handle NULL C prefixes from GIRs

g_irepository_get_c_prefix() can return NULL if the namespace does not
have a defined C prefix. Gracefully handle that.

Based on a patch by Marc-Antoine Perennou <Marc-Antoine@Perennou.com>.
plugin: Enable --quiet if V=0 is set in the environment

Integrate better with the standard automake method of controlling output
verbosity.
tests: Fix a few expected test outputs for gvariant-new.c

Fallout from 234ba46cd95026e763d6a8d7c19cd561c0520ee6.
gir-manager: Handle functions which equal a namespace prefix

The nice() function has the same name as the C prefix for libnice
(‘nice_’), which was causing GirManager::find_function_info() to crash.
gsignal: Fix expected types for enums and flags in signals

Previously they were expected to be passed as pointers, which was not
correct. Now they are expected to be passed by value.
gsignal: Improve error output for boolean types

Previously the error output said an int was expected for boolean
parameters or return types. Now it says a gboolean is expected (which is
equivalent, but clearer).
build: Move AX_CHECK_ENABLE_DEBUG above AM_PROG_CC

Shuts up a warning.
tests: Enable automake’s color-tests option

Colours! Ponies!
scripts: Handle setting CC=tartan correctly

Previously, if the user mistakenly ran Tartan using `make CC=tartan`, it
would error out, as the Clang wrapper script would be invoked with
-add-plugin not escaped by -Xclang. Normally, when the tartan wrapper
script is used, it is passed a -cc1 option, which causes the clang
compiler (not the wrapper script) to be executed, which expects
-add-plugin rather than -Xclang -add-plugin.

Handle this better by checking for the -cc1 argument and adding -Xclang
as appropriate. Also print a warning in the case that the user has
called `make CC=tartan`, as this will only enable the compile-time
checkers, not the static analyser.

Reported by Marc-Antoine Perennou <Marc-Antoine@Perennou.com>.
gsignal: Allow swapped object instances to have actual type gpointer

It seems common to use a gpointer argument for the swapped instance
parameter (i.e. the last argument) to a signal callback, even though
this is not the most specific type known for the variable.

Allow this behaviour — hopefully the programmer is correctly dynamically
casting the gpointer to something more concrete in the callback body.
Either that, or (more likely), ignoring it entirely.