Bootstrap failure on AIX

[CohenArthur]

David Edelsohn said:

I tried bootstrapping gccrs on AIX today and experienced the following error in stage2:

/tmp/RUST/./gcc/xgcc -B/tmp/RUST/./gcc/ -fno-checking -xrust -frust-incomplete-and-experimental-compiler-do-not-use -nostdinc /dev/null -S -o /dev/null -fself-test=/nasfarm/edelsohn/src/gccrs/gcc/testsuite/selftests
/nasfarm/edelsohn/src/gccrs/gcc/rust/lex/rust-lex.cc:2556: assert_source_content: FAIL: ASSERT_EQ ((src_char.value), (expected_char))
crab1: internal compiler error: in fail, at selftest.cc:47

AIX on POWER is big endian and defaults to 32 bit.