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/calls/internal.h

@@ -199,6 +199,8 @@ i64 sys_ptrace(int, i32, void *, void *) hidden;
 i64 sys_pwrite(i32, const void *, u64, i64, i64) hidden;
 i64 sys_pwritev(i32, const struct iovec *, i32, i64, i64) hidden;
 i64 sys_read(i32, void *, u64) hidden;
+i64 sys_readlink(const char *, char *, u64) hidden;
+i64 sys_readlinkat(int, const char *, char *, u64) hidden;
 i64 sys_sendfile(i32, i32, i64 *, u64) hidden;
 i64 sys_splice(i32, i64 *, i32, i64 *, u64, u32) hidden;
 i64 sys_vmsplice(i32, const struct iovec *, i64, u32) hidden;
@@ -290,6 +292,7 @@ int sys_utimensat_nt(int, const char *, const struct timespec *, int) hidden;
 ssize_t sys_open_nt(int, const char *, u32, i32) nodiscard hidden;
 ssize_t sys_read_nt(struct Fd *, const struct iovec *, size_t, ssize_t) hidden;
 ssize_t sys_write_nt(struct Fd *, const struct iovec *, size_t, ssize_t) hidden;
+ssize_t sys_readlinkat_nt(int, const char *, char *, size_t) hidden;
 
 /*───────────────────────────────────────────────────────────────────────────│─╗
 │ cosmopolitan § syscalls » windows nt » support                           ─╬─│┼
@@ -312,6 +315,9 @@ unsigned __wincrash_nt(struct NtExceptionPointers *);
 ssize_t sys_readv_nt(struct Fd *, const struct iovec *, int) hidden;
 ssize_t sys_writev_nt(struct Fd *, const struct iovec *, int) hidden;
 char16_t *CreatePipeName(char16_t *) hidden;
+bool isdirectory_nt(const char *) hidden;
+bool isregularfile_nt(const char *) hidden;
+bool issymlink_nt(const char *) hidden;
 
 /*───────────────────────────────────────────────────────────────────────────│─╗
 │ cosmopolitan § syscalls » metal                                          ─╬─│┼