Reduce header complexity

- Remove most __ASSEMBLER__ __LINKER__ ifdefs
- Rename libc/intrin/bits.h to libc/serialize.h
- Block pthread cancelation in fchmodat() polyfill
- Remove `clang-format off` statements in third_party

third_party/bzip2/blocksort.c

@@ -1,4 +1,3 @@
-/* clang-format off */
 
 /*-------------------------------------------------------------*/
 /*--- Block sorting machinery                               ---*/

third_party/bzip2/bzip2.c

@@ -15,7 +15,6 @@
 #include "libc/time/struct/utimbuf.h"
 #include "libc/time/time.h"
 #include "third_party/bzip2/bzlib.h"
-/* clang-format off */
 
 /*-----------------------------------------------------------*/
 /*--- A block-sorting, lossless compressor        bzip2.c ---*/

third_party/bzip2/bzip2recover.c

@@ -5,7 +5,6 @@
 #include "libc/runtime/runtime.h"
 #include "libc/stdio/stdio.h"
 #include "libc/str/str.h"
-/* clang-format off */
 
 /*-----------------------------------------------------------*/
 /*--- Block recoverer program for bzip2                   ---*/

third_party/bzip2/bzlib.c

@@ -1,4 +1,3 @@
-/* clang-format off */
 
 /*-------------------------------------------------------------*/
 /*--- Library top-level functions.                          ---*/

third_party/bzip2/bzlib.h

@@ -23,7 +23,6 @@
 
 #define BZ_MAX_UNUSED 5000
 
-#if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
 
 typedef struct {
@@ -87,5 +86,4 @@ void BZ2_bzclose(BZFILE *);
 const char *BZ2_bzerror(BZFILE *, int *);
 
 COSMOPOLITAN_C_END_
-#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
 #endif /* _BZLIB_H */

third_party/bzip2/bzlib_private.inc

@@ -2,7 +2,6 @@
 
 #define BZ_NO_STDIO
 
-/* clang-format off */
 
 /*-------------------------------------------------------------*/
 /*--- Private header file for the library.                  ---*/

third_party/bzip2/compress.c

@@ -1,4 +1,3 @@
-/* clang-format off */
 
 /*-------------------------------------------------------------*/
 /*--- Compression machinery (not incl block sorting)        ---*/

third_party/bzip2/decompress.c

@@ -1,4 +1,3 @@
-/* clang-format off */
 
 /*-------------------------------------------------------------*/
 /*--- Decompression machinery                               ---*/

third_party/bzip2/huffman.c

@@ -1,4 +1,3 @@
-/* clang-format off */
 
 /*-------------------------------------------------------------*/
 /*--- Huffman coding low-level stuff                        ---*/

third_party/bzip2/randtable.c

@@ -1,4 +1,3 @@
-/* clang-format off */
 
 /*-------------------------------------------------------------*/
 /*--- Table for randomising repetitive blocks               ---*/

third_party/bzip2/spewG.c

@@ -1,6 +1,5 @@
 #include "libc/stdio/rand.h"
 #include "libc/stdio/stdio.h"
-/* clang-format off */
 
 /* spew out a thoroughly gigantic file designed so that bzip2
    can compress it reasonably rapidly.  This is to help test