Improve library detection in cross-compilation

Autoconf checks for native libraries (when using PKG_CHECK_MODULES) when
cross-compiling, and it shouldn't. Follow the suggestion in
http://stackoverflow.com/questions/12624600 and double-check with
AC_CHECK_LIB. I hate pkg-config.

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>
Update changelog

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>