The detail error message is below.
$ ./configure
$ make
then ...
/usr/share/apr-1/build-1/libtool --silent --mode=link /Applications/Xcode.app/Contents/Developer/Toolchains/OSX10.8.xctoolchain/usr/bin/cc -lssl -lcrypto -lpthread \
-o ab ab.lo -L/usr/lib -R/usr/lib -laprutil-1 -lexpat -liconv -lsqlite3 -lldap -llber -llber -L/usr/lib -R/usr/lib -lapr-1 -lpthread
Undefined symbols for architecture x86_64:
"_TLSv1_1_client_method", referenced from:
_main in ab.o
"_TLSv1_2_client_method", referenced from:
_main in ab.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)