You need to find where your glib-2.0.pc file is located and in then add
PKG_CONFIG_PATH=<path to file> to the end of your ./configure statement.
for example, one that I just a couple minutes ago calling for the exact same thing my configure statement looks like this:
./configure --sbindir=/sbin --datarootdir=/usr/share --sysconfdir=/etc --enable-spoof-source PKG_CONFIG_PATH=/usr/local/lib/pkgconfig --enable-dynamic-linking
Do not copy that exactly as that was designed for a different program I'm compiling, but you can see where you need to add the path.