AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
dnl Test whether trunc() is declared.
AC_CHECK_DECLS([trunc], , , [#include <math.h>])
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
dnl Test whether trunc() is declared.
AC_CHECK_DECLS([trunc], , , [#include <math.h>])