Sync Zend/asm/make_ppc64_sysv_macho_gas.S with upstream (#15769)

There was a typo in make_ppc64_sysv_macho_gas.S with missing closing
multi-line comment. Upstream fixed it in ~2023:
https://github.com/boostorg/context/

Author: petk

Zend/asm/make_ppc64_sysv_macho_gas.S

@@ -64,6 +64,7 @@
  *  |    FCTX   |    DATA   |           |           |  *
  *  -------------------------------------------------  *
  *                                                     *
+ *******************************************************/
 
 .text
 .globl _make_fcontext