Import C++ Standard Template Library

You can now use the hardest fastest and most dangerous language there is
with Cosmopolitan. So far about 75% of LLVM libcxx has been added. A few
breaking changes needed to be made to help this go smoothly.

- Rename nothrow to dontthrow
- Rename nodiscard to dontdiscard
- Add some libm functions, e.g. lgamma, nan, etc.
- Change intmax_t from int128 to int64 like everything else
- Introduce %jjd formatting directive for int128_t
- Introduce strtoi128(), strtou128(), etc.
- Rename bsrmax() to bsr128()

Some of the templates that should be working currently are std::vector,
std::string, std::map, std::set, std::deque, etc.

libc/nexgen32e/bsf.h

@@ -20,7 +20,7 @@ COSMOPOLITAN_C_START_
 int bsf(int) pureconst;
 int bsfl(long) pureconst;
 int bsfll(long long) pureconst;
-int bsfmax(uintmax_t) pureconst;
+int bsf128(uintmax_t) pureconst;
 
 #if defined(__GNUC__) && !defined(__STRICT_ANSI__)
 #define bsf(u)                                                  \

libc/nexgen32e/bsr.h

@@ -20,7 +20,7 @@ COSMOPOLITAN_C_START_
 int bsr(int) pureconst;
 int bsrl(long) pureconst;
 int bsrll(long long) pureconst;
-int bsrmax(uintmax_t) pureconst;
+int bsr128(uint128_t) pureconst;
 
 #if defined(__GNUC__) && defined(__x86_64__) && !defined(__STRICT_ANSI__)
 #define bsr(u)                                                  \

libc/nexgen32e/bsr128.S

@@ -33,7 +33,7 @@
 //	@param	rsi:rdi is 128-bit unsigned 𝑥 value
 //	@return	eax number in range [0,128) or undef if 𝑥 is 0
 //	@see	also treasure trove of nearly identical functions
-bsrmax:	.leafprologue
+bsr128:	.leafprologue
 	.profilable
 	bsr	%rsi,%rax
 	jnz	2f
@@ -41,4 +41,4 @@ bsrmax:	.leafprologue
 1:	.leafepilogue
 2:	add	$64,%eax
 	jmp	1b
-	.endfn	bsrmax,globl
+	.endfn	bsr128,globl