[tests] Set tests machdep to x86_32

tests/basic/aggregate.cpp

tests/basic/extern.cc

tests/basic/extern_static_const.cpp

tests/basic/nullptr_builtin.cpp

tests/basic/static_1.cpp

tests/bts/fixed_from_1757.cpp

tests/bts/preprocessor_1786.cpp

tests/bugs/test_config

tests/da/test_config

tests/exn/all_exn.cpp

tests/exn/integer_exn.cpp

tests/exn/simple_exn.cpp

tests/exn/unsigned_exn.cpp

tests/old/recv.cc

tests/ppwp/test_config

tests/slicing/basic_slice.cc

tests/specs/assigns.cc

tests/specs/extern.cpp

tests/specs/float.cpp

tests/specs/lex.cc