I get an error about undefined macro: AC_MSG_ERROR. What's up?
The error message is misleading. The actual cause is that aclocal fails to pull in the definition for PKG_CHECK_MODULES. Make sure you have pkg-config installed.
This will force all of the necessary packages to be reinstalled even if present, in case they're broken and your system doesn't realize it. Then give it another go and let us know the results.