va_vopy() is not universally available in all compilers, so make use of
the existing G_VA_COPY macro which either calls va_copy() if it is
available, or emulates it if otherwise.
The documentation for G_TYPE_CHAR says:
"The type designated by G_TYPE_CHAR is unconditionally an 8-bit signed
integer."
However the return value for g_value_get_char() was just "char" which
in C has an unspecified signedness; on e.g. x86 it's signed (which
matches the GType), but on e.g. PowerPC or ARM, it's not.
We can't break the old API, so we need to suck it up and add new API.
Port most internal users, but keep some tests of the old API too.
https://bugzilla.gnome.org/show_bug.cgi?id=659870
To help cross compilation, don't use glib-genmarshal in our
build. This is easy now that we have g_cclosure_marshal_generic().
In gobject/, add gmarshal.[ch] to git (making the existing entry
points stubs).
In gio/, simply switch to using g_cclosure_marshal_generic().
https://bugzilla.gnome.org/show_bug.cgi?id=652168
