Enable tail calling only when large structs can be returned via registers

 * Enable tail calling only on x86_64 and arm64
 * On Windows with Clang, force SysV ABI on helpers with extra args (helpers
   which return zend_vm_trampoline)

Author: arnaud-lb

Zend/zend_portability.h

@@ -330,6 +330,11 @@ char *alloca();
 #  define ZEND_MUSTTAIL __attribute__((musttail))
 #endif
 
+#if __has_attribute(sysv_abi)
+#  define HAVE_SYSV_ABI
+#  define ZEND_SYSV_ABI __attribute__((sysv_abi))
+#endif
+
 #if (defined(__GNUC__) && __GNUC__ >= 3 && !defined(__INTEL_COMPILER) && !defined(__APPLE__) && !defined(__hpux) && !defined(_AIX) && !defined(__osf__)) || __has_attribute(noreturn)
 # define HAVE_NORETURN
 # define ZEND_NORETURN __attribute__((noreturn))