Update libplist in configure.ac

[josh-]

I wasn't able to build idevicelocation due to an inability for configure.sh to find libplist that was installed through Homebrew:

configure: error: Package requirements (libplist >= 0.15) were not met:

No package 'libplist' found

Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.

$ brew list libplist 
/usr/local/Cellar/libplist/2.2.0/bin/plistutil
/usr/local/Cellar/libplist/2.2.0/include/plist/ (14 files)
/usr/local/Cellar/libplist/2.2.0/lib/libplist++-2.0.3.dylib
/usr/local/Cellar/libplist/2.2.0/lib/libplist-2.0.3.dylib
/usr/local/Cellar/libplist/2.2.0/lib/pkgconfig/ (2 files)
/usr/local/Cellar/libplist/2.2.0/lib/ (4 other files)
/usr/local/Cellar/libplist/2.2.0/share/man/man1/plistutil.1

This appears to be because the libplist binary was recently renamed: libimobiledevice/libplist#163, libimobiledevice/libplist@137716d. Updating the module name then allows idevicelocation to be built successfully with the latest version of libplist.

[benji2512]

Recently came across this when building this via Nix. Might be worth merging into master to avoid any further confusing ?