mescc: Support regular C99 compile, headers + mlibc.

mescc: Support regular C99 compile, headers + mlibc.

* libc/include/assert.h: New file.
* libc/include/ctype.h: New file.
* libc/include/errno.h: New file.
* libc/include/fcntl.h: New file.
* libc/include/limits.h: New file.
* libc/include/mlibc.h: New file.
* libc/include/stdio.h: New file.
* libc/include/stdlib: New file.
* libc/include/string.h: New file.
* libc/include/unistd.h: New file.
* libc/mlibc.c: Remove declarations.
* make/bin.make (INCLUDES): Factor out standard includes.
* make/bin-mlibc.make: New file.
* scaffold/scaffold.make: Use it.
* src/src.make: Use it.
* module/language/c99/compiler.mes (ast-info): Handle more function declarations.
* scaffold/cons-mes.c: Remove mlibc definitionsa and mlibc.c include.
  Instead include <mlibc.h>.
* scaffold/hello.c: Likewise.
* scaffold/m.c: Likewise.
* scaffold/malloc.c: Likewise.
* scaffold/micro-mes.c: Likewise.
* scaffold/mini-mes.c: Likewise.
* scaffold/t.c: Likewise.
* scaffold/tiny-mes.c: Likewise.
* src/gc.c: Likewise.
* src/lib.c: Likewise.
* src/math.c: Likewise.
* src/mes.c: Likewise.
* src/posix.c: Likewise.
* src/reader.c: Likewise.