***** autoconf *****
***** PWD: /var/tmp/portage/media-libs/libmp4v2-1.5.0.1-r2/work/mpeg4ip-1.5.0.1
***** autoconf

configure.in:269: warning: AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS
../../lib/autoconf/specific.m4:386: AC_USE_SYSTEM_EXTENSIONS is expanded from...
../../lib/autoconf/specific.m4:332: AC_GNU_SOURCE is expanded from...
configure.in:269: the top level
configure.in:269: warning: AC_RUN_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS
configure.in:645: error: possibly undefined macro: AM_PATH_GTK_2_0
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.