https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100014
--- Comment #2 from Andreas Schwab <sch...@linux-m68k.org> ---
According to the autoconf docs, it should work also when cross-compiling:
This macro runs a test-case if endianness cannot be determined
from the system header files. When cross-compiling, the test-case
is not run but grep'ed for some magic values. ACTION-IF-UNKNOWN
