Undiamond Python headers

This change gets the Python codebase into a state where it conforms to
the conventions of this codebase. It's now possible to include headers
from Python, without worrying about ordering. Python has traditionally
solved that problem by "diamonding" everything in Python.h, but that's
problematic since it means any change to any Python header invalidates
all the build artifacts. Lastly it makes tooling not work. Since it is
hard to explain to Emacs when I press C-c C-h to add an import line it
shouldn't add the header that actually defines the symbol, and instead
do follow the nonstandard Python convention.

Progress has been made on letting Python load source code from the zip
executable structure via the standard C library APIs. System calss now
recognizes zip!FILENAME alternative URIs as equivalent to zip:FILENAME
since Python uses colon as its delimiter.

Some progress has been made on embedding the notice license terms into
the Python object code. This is easier said than done since Python has
an extremely complicated ownership story.

- Some termios APIs have been added
- Implement rewinddir() dirstream API
- GetCpuCount() API added to Cosmopolitan Libc
- More bugs in Cosmopolitan Libc have been fixed
- zipobj.com now has flags for mangling the path
- Fixed bug a priori with sendfile() on certain BSDs
- Polyfill F_DUPFD and F_DUPFD_CLOEXEC across platforms
- FIOCLEX / FIONCLEX now polyfilled for fast O_CLOEXEC changes
- APE now supports a hybrid solution to no-self-modify for builds
- Many BSD-only magnums added, e.g. O_SEARCH, O_SHLOCK, SF_NODISKIO

libc/nexgen32e/ktolower.S

@@ -18,23 +18,17 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/macros.internal.h"
 
+	.initbss 300,_init_kToLower
 //	ASCII uppercase → lowercase translation tables.
 //
 //		char kToLower[256];
-//		char16_t kToLower16[256];
 //
-//	@note	kToLower16 saves 128kb; CMOVcc can't even 8-bit
-	.initbss 300,_init_kToLower
+//	@see	kToUpper
 kToLower:
 	.rept	256
 	.byte	0
 	.endr
 	.endobj	kToLower,globl,hidden
-kToLower16:
-	.rept	256
-	.short	0
-	.endr
-	.endobj	kToLower16,globl,hidden
 	.previous
 
 	.init.start 300,_init_kToLower
@@ -44,17 +38,11 @@ kToLower16:
 	xor	%ecx,%ecx
 0:	inc	%ecx
 	addb	$0x20,'A'-1(%rsi,%rcx)
-	cmp	$'Z'-'A',%ecx
+	cmp	$'Z'-'A'+1,%ecx
 	jne	0b
-	xor	%eax,%eax
-	mov	$256,%ecx
-0:	lodsb
-	stosw
-	.loop	0b
 	pop	%rsi
 	.init.end 300,_init_kToLower
 
 	.type	gperf_downcase,@object
 	.globl	gperf_downcase
 	gperf_downcase = kToLower
-	.source	__FILE__