Improve Libc by making Python work even better

Actually Portable Python is now outperforming the Python binaries
that come bundled with Linux distros, at things like HTTP serving.
You can now have a fully featured Python install in just one .com
file that runs on six operating systems and is about 10mb in size.
With tuning, the tiniest is ~1mb. We've got most of the libraries
working, including pysqlite, and the repl now feels very pleasant.
The things you can't do quite yet are: threads and shared objects
but that can happen in the future, if the community falls in love
with this project and wants to see it developed further. Changes:

- Add siginterrupt()
- Add sqlite3 to Python
- Add issymlink() helper
- Make GetZipCdir() faster
- Add tgamma() and finite()
- Add legacy function lutimes()
- Add readlink() and realpath()
- Use heap allocations when appropriate
- Reorganize Python into two-stage build
- Save Lua / Python shell history to dotfile
- Integrate Python Lib embedding into linkage
- Make isregularfile() and isdirectory() go faster
- Make Python shell auto-completion work perfectly
- Make crash reports work better if changed directory
- Fix Python+NT open() / access() flag overflow error
- Disable Python tests relating to \N{LONG NAME} syntax
- Have Python REPL copyright() show all notice embeddings

The biggest technical challenge at the moment is working around
when Python tries to be too clever about filenames.

libc/sysv/syscalls.sh

@@ -128,7 +128,7 @@ scall	sys_creat		0xffffff008ffff055	globl hidden
 scall	sys_link		0x0090090092009056	globl hidden
 scall	sys_unlink		0x00a00a00a200a057	globl hidden
 scall	sys_symlink		0x0390390392039058	globl hidden
-scall	readlink		0x03a03a03a203a059	globl        # usually an anti-pattern
+scall	sys_readlink		0x03a03a03a203a059	globl hidden # usually an anti-pattern
 scall	sys_chmod		0x00f00f00f200f05a	globl hidden
 scall	sys_fchmod		0x07c07c07c207c05b	globl hidden
 scall	sys_chown		0x010010010201005c	globl hidden # impl. w/ fchownat() @asyncsignalsafe
@@ -162,7 +162,7 @@ scall	sys_setresuid		0xfff11a137ffff075	globl hidden # polyfilled for xnu
 scall	sys_setresgid		0xfff11c138ffff077	globl hidden # polyfilled for xnu
 scall	getresuid		0xfff119168ffff076	globl # semantics aren't well-defined
 scall	getresgid		0xfff11b169ffff078	globl # semantics aren't well-defined
-scall	sigpending		0x124034034203407f	globl
+scall	sigpending		0x124034034203407f	globl # rt_sigpending on linux
 scall	sys_sigsuspend		0x12606f155206f082	globl hidden # openbsd:byvalue
 scall	sigaltstack		0x1191200352035083	globl
 scall	sys_mknod		0x1c200e00e200e085	globl hidden
@@ -700,7 +700,7 @@ scall	lchflags		0x130fff187fffffff	globl
 scall	lchmod			0x112fff112fffffff	globl
 scall	lgetfh			0xffffff0a0fffffff	globl
 scall	lpathconf		0x1f3fff201fffffff	globl
-scall	lutimes			0x1a8fff114fffffff	globl
+scall	sys_lutimes		0x1a8fff114fffffff	globl hidden
 scall	mac_syscall		0xffffff18afffffff	globl
 scall	modfind			0xffffff12ffffffff	globl
 scall	modfnext		0xffffff12efffffff	globl