+dnl Require pkg-config
+m4_ifndef([PKG_PROG_PKG_CONFIG],
+ [m4_fatal([Could not locate the pkg-config autoconf macros. These
+are usually located in /usr/share/aclocal/pkg.m4. If your macros
+are in a different location, try setting the environment variable
+ACLOCAL_FLAGS before running ./autogen.sh or autoreconf again. E.g.:
+export ACLOCAL_FLAGS="-I/other/macro/dir"])
+])