Make improvements

- Fix unused local variable errors
- Remove yoinks from sigaction() header
- Add nox87 and aarch64 to github actions
- Fix cosmocc -fportcosmo in linking mode
- It's now possible to build `make m=llvm o/llvm/libc`

libc/x/xsigaction.h

@@ -6,14 +6,6 @@ COSMOPOLITAN_C_START_
 
 int xsigaction(int, void *, uint64_t, uint64_t, struct sigaction *);
 
-#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
-#define xsigaction(SIG, HANDLER, FLAGS, MASK, OLD) \
-  ({                                               \
-    __SIGACTION_YOINK(SIG);                        \
-    xsigaction(SIG, HANDLER, FLAGS, MASK, OLD);    \
-  })
-#endif
-
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
 #endif /* COSMOPOLITAN_LIBC_X_XSIGACTION_H_ */