__uint128_t support in gobject introspection

[Mark Salter <msalter redhat com>]

I ran into an issue in gobject-introspection while bootstrapping fedora
packages for AArch64. I was able to build gobject-introspection but when
some other packages run the scanner, I see:

  /usr/include/asm/sigcontext.h:53: syntax error, unexpected identifier in ' __uint128_t vregs[32];' at 
'__uint128_t'
  /usr/include/asm/ptrace.h:75: syntax error, unexpected identifier in ' __uint128_t vregs[32];' at 
'__uint128_t'
  /usr/include/asm/sigcontext.h:53: syntax error, unexpected identifier in ' __uint128_t vregs[32];' at 
'__uint128_t'

So, aarch64 gcc has a builtin __uint128_t which the kernel exposes in
some of its headers. It seems like gobject-introspection about this
type. Am I missing anything? It sees like an easy enough thing to do
from a quick glance at the code, but I could just be naive about it.

--Mark