Make improvements

This change progresses our AARCH64 support:

- The AARCH64 build and tests are now passing
- Add 128-bit floating-point support to printf()
- Fix clone() so it initializes cosmo's x28 TLS register
- Fix TLS memory layout issue with aarch64 _Alignas vars
- Revamp microbenchmarking tools so they work on aarch64
- Make some subtle improvements to aarch64 crash reporting
- Make kisdangerous() memory checks more accurate on aarch64
- Remove sys_open() since it's not available on Linux AARCH64

This change makes general improvements to Cosmo and Redbean:

- Introduce GetHostIsa() function in Redbean
- You can now feature check using pledge(0, 0)
- You can now feature check using unveil("",0)
- Refactor some more x86-specific asm comments
- Refactor and write docs for some libm functions
- Make the mmap() API behave more similar to Linux
- Fix WIFSIGNALED() which wrongly returned true for zero
- Rename some obscure cosmo keywords from noFOO to dontFOO

Makefile

@@ -66,7 +66,7 @@ MAKEFLAGS += --no-builtin-rules
 .SUFFIXES:
 .DELETE_ON_ERROR:
 .FEATURES: output-sync
-.PHONY: all o bins check test depend tags
+.PHONY: all o bins check test depend tags aarch64
 
 ifneq ($(m),)
 ifeq ($(MODE),)
@@ -267,7 +267,7 @@ CHECKS	 = $(foreach x,$(PKGS),$($(x)_CHECKS))
 
 bins:	$(BINS)
 check:	$(CHECKS)
-test:	$(TESTS)
+test:	$(TESTS) aarch64
 depend:	o/$(MODE)/depend
 tags:	TAGS HTAGS
 
@@ -424,6 +424,10 @@ toolchain:	o/cosmopolitan.h				\
 		o/$(MODE)/cosmopolitan.a			\
 		o/$(MODE)/third_party/libcxx/libcxx.a
 
+aarch64: private .UNSANDBOXED = true
+aarch64:
+	$(MAKE) m=aarch64
+
 # UNSPECIFIED PREREQUISITES TUTORIAL
 #
 # A build rule must exist for all files that make needs to consider in