This issue occurs when compiling on Power8. This is as a result of a rather old config.guess file which is included in the src folder of libfaac.
Attempting to ./configure the libfaac packages ends with the following output.
config.guess timestamp = 2006-07-02
uname -m = ppc64le
uname -r = 3.13.0-37-generic
uname -s = Linux
uname -v = #64-Ubuntu SMP Mon Sep 22 21:27:09 UTC 2014
/usr/bin/uname -p =
/bin/uname -X =
/usr/bin/arch -k =
UNAME_MACHINE = ppc64le
UNAME_RELEASE = 3.13.0-37-generic
UNAME_SYSTEM = Linux
UNAME_VERSION = #64-Ubuntu SMP Mon Sep 22 21:27:09 UTC 2014
configure: error: cannot guess build type; you must specify one
Download a proper config.guess that is able to determine the power8 architecture.
Download a modernized config.guess file and overwrite the one in src folder that you are attempting to configure.
Re-run the ./configure command and everything should work as expected.
You can download a sample config.guess file below.