The payload is likely to play games with the stack area (like mmap()ing guard
pages), so give it virtual memory to play with instead of physical memory.

Fixes crash with mode=release.

glibc headers define various standard functions as macros, which breaks
the build.  #undef them in the source files.

We want these in line buffered mode, but to get that we need to query the
console driver if it is a tty, and we can only do that after the VFS has
been brought up.

except for the floating point functionality for now.

We did not account for negative numbers, oops.

This would require pulling in libm, for which we aren't ready yet.

note that as of now all functioanlity related to file or pthread locking
is not implemented or stubbed out.

Pretend we're another OS to avoid confusing the payload.

Java stomps all over a 64k stack.

The pthread_self() implementation was inconsistent with pthread_create(),
leading to corruption.  Switch to a simpler implementation using
thread-local storage.

Needed for pthread_attr_*() (and in general to make sure the stack is
a regular vma as expected by the payload).

We now have a common set of flags for C and C++, but also allow C-only flags,
which are used to:

  a) enable C99+GNU mode
  b) include the libc internal headers

although the latter could be refined even more.

Import the whole string library, as well as the ctype functions from the musl
C library.  Must is a BSD licensed library that aims to be API and mostly ABI
compatible with glibc, so it's our easiest way to provide the ABI we need
without reinventing the wheel.  I will import more of the traditional non-syscall
C library code from it and expect libc/ to eventually mostly consist of slightly
modified musl code.

Fox simplicity, the first mutex implementation will not be compatible with
PTHREAD_MUTEX_INITIALIZER, so wrap the mutex class with a structure that also
contains an intitialization flag, and initialize it on demand.

There now is a public add_object and a private set_object method, which
describe the two totally different actions much better.

Apparently glibc defines it as a macro, so it doesn't compile.  #undef it
back.

Instead of using the variable's value, we used its name.

There isn't even a name for this kind of bug.