[pushed] Handle complex error type in read_base_type
It turns out there was one more bug in the earlier complex series:
read_base_type could cause an assertion failure on some platforms. I
found this running the AdaCore internal test suite, but you can also
see it by running gdb's "gdb.cp" tests for x86 (not x86-64).
In particular, the DW_ATE_complex_float case calls
dwarf2_init_complex_target_type, which calls dwarf2_init_float_type,
which can return a type using TYPE_CODE_ERROR.
This patch changes the DWARF reader to handle this case, the same way
that the f-lang.c patch did. Perhaps init_complex_type really should
be changed to allow TYPE_CODE_ERROR? I was not sure.
Tested on x86-64 Fedora 30, using an x86 build. I'm checking this in.