First, try it using the src2pkg command instead of trackinstall:
src2pkg glib-2.22.0.tar.??
I suspect you may need to use:
src2pkg -DEST glib-2.22.0.tar.??
With the new src2pkg-2.0, the default INSTALL_TYPE has been made JAIL, but it fails with some packages. Anytime you have a failure such as this, it is worth trying one of the alternate content-creation methods. There are five in total:
JAIL, DEST(or DESTDIR), UNION, SAFE and REAL

Thanks for your suggestions. I didn't expect your response to be that quick, and I duplicated my post, please ignore.

Are you saying that src2pkg can take over the entire configuration
and compilation of just about any installed program? What if I need
to pass flags to <configure> or <make>?

.................................................................
EDIT: Wow, it worked, I'm impressed The first time round I tried

src2pkg glib-2.22.0.tar.gz

and got the same installation error as before. But

src2pkg -DEST glib-2.22.0.tar.gz

worked perfectly through all the stages (configuration, make,
make install) and created the Slackpack ready for use with
installpkg.

Thankyou very much gnashley

.................................................................
SECOND EDIT:

-DEST doesn't seem to work as a flag to trackinstall?
Can that be fixed?

I'll look into the problem with DEST using trackinstall.
Yes, you can use src2pkg for the whole build. It will nearly always be more dependable because it gets tested more. There are a very few cases where trackinstall may give better results. Run 'src2pkg --help' to see the main options or look at the man-page. Passing options to configure is the most commonly-needed feature -you simply use, for example:
src2pkg -e='--disable cruft --enable-goodies' tarball-name
But, if you are using extra options, it really is a good idea to create a src2pkg script so you have a record of what you did. In such a case, you can do this:
src2pkg -e='--disable cruft --enable-goodies' -N tarball-name
The '-N' tells src2pkg to create the script for you. Then, you can run the script by simply using:
src2pkg -X
Note that you can still add other (Captial-lettered) options when using the '-X', option:
src2pkg -X -C -W -DEST
(Run the first script you find, place the final package in the Current directory, cleanup (Wipe up) temporary files when finished, use DESTDIR-type installation for creation of content)
This is handy because it lets you use 'hard copy' options which are essential to the package (configure options, make command, etc), while still having use of a range of transient options for user-oriented beahviours -and keeping the command-line shorter.
Thanks for the tip on -DEST and trackinstall.

I just upgraded to src2pkg-2.0-noarch-16.tgz after grabing latest updates from slackware64-current. While running 'src2pkg --setup' created and installed helpers successfully, during compiling it complained about 'Creating libsentry - Ooops! Can't live without it...'. Afterwards running 'src2pkg package.tar.gz' still gave this notice:
Is 'libsentry' a missing dependency?

libsentry (as well as a few other things) is distributed with src2pkg as source and is built by src2pkg --setup

confirmed this!
When use src2pkg with root, it always compile src2pkg-helpers first...
again and again.

I am using slackware current.
during compiling it complained about 'Creating libsentry - Ooops! Can't live without it...'

It's ok under slackware 12.2.
just print 'Creating libsentry - Ok'

Yeah, libsentry is a must-have. Current just switched to glibc-2.11.1 the other day and I'm pretty sure this is what is keeping libsentzry/src2pkg-helpers from building.
veall and zhoun, can you both send me an email so I can send you a newer copy of src2pkg-helpers or the full pre-release src2pkg so you can see if it now builds?
I've been planning on releasing again real soon -this just makes it more pressing...

this is the error

Yeah, I think I've fixed that already as I ran into it the other day. I rolled in some fixes for glibc>=2.10 that adress that and some 64-bit issues.

Anyone running slackware64-current who can test these fixes?

I just installed src2pkg and ran src2pkg --setup with no problems on x64-current.

Oh really? So maybe it is working on 64-bit, but not on 32 -sounds backwards...

I should have added that I am running the multilib version. That may be important.

I can also confirm this on current 32bit

No, its not working. Only the install and setup ran ok. Running src2pkg on a tarball still gives notice that helpers needs updating and it seems to rebuild libsentry and coreutils. Then it goes on with the build.

Okay, sorry it is late here in Germany so I must work on this tomorrow with a fresh start... Thanks to all for the feedback.