autogen.sh should check pkg-config's presence
I've stuck on building libxml2 for a couple of days by the following error message:
$ ./autogen.sh <stripped...> Checking zlib ./configure: line 13072: syntax error near unexpected token `Z,zlib,' ./configure: line 13072: ` PKG_CHECK_MODULES(Z,zlib,' Now type 'make' to compile libxml2. $ make make: *** No targets specified and no makefile found. Stop.
and later found out it is due to the missing pkg-config dependency, which is not documented in the F.A.Q.. IMO the autogen or the configure script should warn about this.