Add support for marshalling void*

void pointers are sometimes used for tags, such as in GtkTreeIter,
so it is useful to have basic marshalling implemented.
Note that they're treated like integers, and marshalled as doubles
in 64-bit arches, so there is no memory management involved.

https://bugzilla.gnome.org/show_bug.cgi?id=700643
25 jobs for wip/gcampax/700643-allow-creating-custom-tree-models in 2 minutes and 8 seconds (queued for 7 seconds)
latest
Status Job ID Name Coverage
  Source Check
passed #138741
cppcheck

00:00:35

passed #138742
cpplint

00:00:44

passed #138743
eslint

00:00:37

failed #138740
fedora

00:02:08

 
  Test
skipped #138746
no_graphics
skipped #138747
no_profiler
skipped #138748
no_readline
skipped #138744
sanitizer_gcc
skipped #138745
with_logging
 
  Manual
skipped #138762
allowed to fail manual
armv8
skipped #138749
allowed to fail manual
codequality
skipped #138750
allowed to fail manual
code_statistics
skipped #138764
allowed to fail manual
coverage
skipped #138752
allowed to fail manual
fedora_gcc
skipped #138758
allowed to fail manual
flatpak
skipped #138753
allowed to fail manual
installed_tests
skipped #138756
allowed to fail manual
lts
skipped #138763
allowed to fail manual
ppc64le
skipped #138751
allowed to fail manual
sanitizer_clang
skipped #138755
allowed to fail manual
ubuntu_clang
skipped #138754
allowed to fail manual
ubuntu_gcc
skipped #138757
allowed to fail manual
valgrind
skipped #138761
allowed to fail manual
zeal_11
skipped #138759
allowed to fail manual
zeal_2
skipped #138760
allowed to fail manual
zeal_4
 
Name Stage Failure
failed
fedora Source Check
configure: found 1 matching files                  
Makefile: found 1 matching files

analysis/: found 2 matching files

./*.log: found 4 matching files

./*.trs: found 1 matching files

./installed-tests/scripts/*.log: found 2 matching files

./installed-tests/scripts/*.trs: found 2 matching files

Uploading artifacts to coordinator... ok
id=138740 responseStatus=201 Created token=zpo6RkhJ
ERROR: Job failed: exit code 1