_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.
the 4.4BSD non-shared-address-space semantics), and direct the user to
include <unistd.h> to generate the correct reference.
This warning isn't about an ABI compatibility issue, but the new vfork() is
considerably faster.