_ASM_LABEL(cerror) and _ASM_LABEL(curbrk) to _C_LABEL(__cerror) and
_C_LABEL(__curbrk) (or their respective architecture-specific equivalents) to
avoid possible name clashes with identifiers used in user applications.
* Do the same for minbrk on all architectures to avoid a GCC-specific (and
on ELF architectures effectively useless) symbol reference renaming in MI code.
Explicilty reload the mips-ABIcall GOT/$gp in cerror().
cerror() gets called from outside libc (e.g., from libposix's rename(),
and if we don't load $t9, cerror() makes wild references using
the libposix $gp and coredumps.